Mr. T (MrT4) said:

The interesting bit is that large armies probably due to the cost and numbers required use a lot of APC 8x8 with 12.7 or 40mm RWS while small eastern european countries opted for much heavier armament.

Its a bit more complicated.
Most of the heavy weight 8x8 are heavy because of the mission profile and environment they have been developed for.
The boxer originally started as a replacement for the Fuchs, VAB/AMX-10P, M113 and similar vehicles. Its developement started in the first half of the '90. At this point we talk about a 20-25 t vehicle. Its weight and size grew as a result of requirement creep. Which caused the French to leave the program and develope the VBCI and VBMR. The resulting vehicle while really good ended up being massive and heavy. A 1 for 1 replacement as originally intended was not feasible anymore. So the number procured was lowered. This is why the Boxers originally used by Germany and others are only lightly armed. They are not intended as wheeled IFV, FSV or something like that. They are simply APCs and equipment carriers with no real combat function.
The other heavy 8x8 also got heavy because of the extreme focus on protection that became fancy during the GWoT era.
Striker is a litte special again because there have been limiting strategic mobility requirements. Which conciderably limited the capabilities of the vehicle. Since Striker was never really intended for HIC or a near peer war light armament was concidered sufficient. A larger weapon also would have been to heavy.
Once the heavy and well protected 8x8 APCs became available someone figured out they could carry decent armament and work as wheeled IFV replacement. Once these found customers and proved usable and usefull the original users of the heavy 8x8 also started to buy them.

Mr. T (MrT4) said:

But on the othe other hand if you look at the Baltics there is renewed interest in 6x6 APCs as a cheap addition to these wheeled quasi IFVs

This is everywhere now. The French went with the 6x6 VBMR. The German Army still uses the Fuchs and still grades it up. Germany also recently joined the CAVS program to get a new 6x6 to replace the Fuchs fleet. Its quite ironic since these will do what Boxer originally was supposed to do while Boxer now fills roles that originally (in the '90) have not filled by Fuchs. It has finally dawened on the decision makers that you can not effectively replace a sub 20 t 6x6 with a allmost 40 t vehicle.

Mr. T (MrT4) said:

Seeing the utility of the 30mm US decided to upgrade at 6 Striker brigades with 30mm turret replacing the 12.7mm til '27

It was more because of the changes in the global environment. A serious weapon simply was needed and being Ro-Ro capable in a C-130 became less important. Which makes a lot of sense.

Mr. T (MrT4) said:

When it comes to turrets, in 2018 the cost of Elbit UT-30 Mk2 was around 1.3mio Eur but sans cannon , i have no clue how much a 30mm cannon costs , but i know the addition of Spike ATGMs was a 0.5mio+ option.

These deals usually also include spare parts, tools, training equipment, documentation etc. So the complete cost of a procurement program usually does not give the unit prive by simply diving cost by number of vehicles or items delivered.
This for example is why its so expensive to introduce new equipment. Buying somthing you allready have is rather cheap in comparison.

Well armed 8x8 past and present

Land 400 theoretical application

It's fascinating how large these wheeled vehicles have gotten.  Here's another size comparison (Namer vs Eitan). 

To think Namer can potentially resist a 125mm frontally while Eitan likely wouldn't survive a 35mm...

Crazy size for battle taxi 

35-40 ton 8x8 to carry 6-8 dismounts at near 10mio Eur a piece, and then you end up buying 15-24 ton 6x6 to do the work 8x8 was supposed to do while 8x8 pretends to be an IFV

Like Patria 6x6, Pandur 6x6 etc 10 dismounts plus a crew of two, driver and commander,

YouTube

Patria 6x6, APC, troop transport - Focus on essentials

Patria 6x6 - Focus on essentialsIn modern warfare, the need for large tactical troop transportation is still existing. Patria 6x6 vehicle is built on the her...

Amphibious MRAP like Protolab PMPV that supposedly costs under 1 million in base variant

https://twitter.com/i/status/1128247756496211968

Sisu GTP 2+8 dismounts

Refleks said:

It's fascinating how large these wheeled vehicles have gotten. Here's another size comparison (Namer vs Eitan). To think Namer can potentially resist a 125mm frontally while Eitan likely wouldn't survive a 35mm...

Don't make the mistake to confuse size with mass and either with capability.
The 8x8 are so large because the wheels need to have huge diameters. This raises axle hight wich increases overall vehicle height. The huge wheels and the large motions they are capable off are the main reason why modern 8x8 have such good cross country mobility.
This is not directly linked to weight. Even lightweight 8x8 or 6x6 will use such wheels and are high as a result.
In addition there are modern ergonomic requirements and blast protection. Which eats up space like crazy. The old vehicles like LAV/Piranha, Luchs, all BTRs etc have horrible blast protection. Which either limited their usefullness or caused major upgrades which conciderable increased weight and had negative impact on mobility.
The Eitan weights only half as much as a Namer. Roughly. Yet it carries more troops. Its usable interiour volume is actually larger. But its protection is not nearly as good... protection against direct attack with large caliber AP shots that is. The Eitan has significant protection (at least K4) and is equiped with an ADS. So against a lot of threats is pretty well equiped. Since its not supposed to go head on with tanks its protection certainly is adequate.

Mr. T (MrT4) said:

35-40 ton 8x8 to carry 6-8 dismounts at near 10mio Eur a piece

A Boxer doesn't cost 10 mio €. The common versions are all around 5 mio € and the armed IFV versions in the 6-7 mio € range.

Mr. T (MrT4) said:

Like Patria 6x6, Pandur 6x6 etc 10 dismounts plus a crew of two, driver and commander,

Neither of these is nearly as capable as the heavy 8x8. The protection of the Patria 6x6 is a joke by modern western standards. Its also not small. Its about as large as a Boxer. Its just lighter. Which is a direct result of its poor protection. If the protection is increased its weight goes up conciderably compromising its off road mobility and it definetly won't swim anymore.
The Patria AMV which is comparable to the Eitan and Boxer in capablility is, supprise, supprise, as large and heavy.

The older lighter and smaller 8x8 and the current 6x6 simply do not fill the same role as the heavy 8x8. The latter ones are capable of operating on the frontline and at an high threat environment typical for COIN and LIC.
The first two are intended for support roles. Not to be shot at or really fight. It attacked they where supposed to smoke and run. With their light armament giving limited self defense capablity. This concept has not worked in the COIN and LIC deployments typical for the first two decades of the century. The heavy 8x8 bunkers on wheels are the result. Not protected and cross country mobile support vehicles are needed again. Hence a renewed intrest in ligher 8x8 and 6x6. But these are not supposed to replace the heavy 8x8 but supplement them.

If you are intrested I recently got some insight in the German procurement program for a 6x6 Fuchs replacement. Why the CAVS program has been joined and most important why there are such drastical differences in price of the different 6x6 vehicles offered.

Definitely interested, as it looks like 6x6 are being resurrected .

As for the Germans joining the CAVS program: this is a move from the MoD. It caught anybody involved in the Fuchs replacement program, one of the slow burners running for years, by supprise. It seems the MoD wants additional contenders for the Fuchs replacement than just Rheinmetall with the high roof Fuchs 1A9. Which actually is a typical German procurement program with the 1A9 directly tailored to the requirements. Since lately Latvia has purchased some Patria 6x6 for ~1 Million € a piece and the price Rh calls for the 1A9 is more than twice that someone in the German MoD decided it might be a good idea and bring Patria into the race. Which at first glance seems like a smart idea.

Now here is the but. A really huge but. As mentioned the 1A9 is tailored to exactly fit the existing requirement for the Fuch replacement. The Patria is not. It turns out after even a brief reading trough the specs that the Patria doesn't even come close to fullfilling the German requirements. Lativia purchased a really basic version. That even lacks essential equipment like NBC-protection, a fire supression system etc. Furthermore the protection is really basic too. STANAG K2 and B2. Since the Fuchs replacement is supposed to operate together with the Boxer fleet a comparable protection level is needed. The Latvian Patria doesn't even have decoupled seating. The engine the Latvians use is a truck engine. Not mil spec. An off the shelf truck engine. Its power to weight ratio (with STANAG 2) is below the German requirement. It also lacks features like day and night vision systems. Of course Patria confirms that the CAVS can be modified to meet the German standards and requirements... but it will definitly not cost 1 Mio. € per vehicle after that anymore.
The Fuchs replacement program really is going to get intresting. The recon and engineer corps, heavy users of the Fuchs, allready added the requirement for the replacement to be amphibious. The Fuchs is the last amphibious vehicles they have. If this capability is going to be retained without purchasing special vehicles the new Fuchs besides having conciderable protection requirements also needs to be able to swim.
 

It really comes down to the details and capabilities. If you want a truck to carry stuff and people around with some armor you can get this rather cheap. Allthough I would argue a Griffon 6x6 or Eagle V 6x6 are a better choice for this than a basic CAVS. If you want/need the capabilities of a real AFV as APC you have to pay for it.

This for example is why the Boxer is so expensive. Its a true AFV. Its better protected than most APC and lots of IFV regardless if tracked or wheeled. At the same time it has really good mobility. Behond what an armored truck can achieve. This of course costs money.

https://euro-sd.com/2020/02/articles/15949/the-return-of-the-6x6-afv/#:~:text=The%20Return%20of%20the%206%C3%976%20AFV%207.%20February,a%20number%20of%20new%20designs%20already%20in%20production.

As seen in the article above, the tyranny of the land and poor infrastructure of less than developed countries has kept the 6x6 alive in theaters usually with less focused internet exposure than the fancy 8x8 contracts. The Guarani is one of those programs whereas the best substitute for a 6x6 (Urutu/Cascavel) is another 6x6. Although the ENGESA golden years will be well missed, the occasional small export batch (Phil, Libano, etc) keeps the concept viable internally and externally.