stancrist said:

Work in close cooperation with tanks. Go where tanks go. Carries infantry. That's what the APC was designed to do. Sure seems like the same mission.

No its not.

In the video it even says the APCs need to be backed up by tanks. In other words they are not supporting the tanks. They are slowing them down.
Since an APC needs to deploy its troops and prefereably stay out of harms way because it lacks protection. It can't duel.
The M113 is a prime example. It can not operate close to tanks because its to slow, lacks protection and it doesn't really bring any mounted firepower. The only thing it brings is dismounts. And this rather slow I would add.
An M113 doesn't compare to a Marder or a Bradley.

schnuersi said:

       RovingPedant said: I'm of the opinion that an IFV is a subset of APC.

A common mistake. The IFV is a subset of the tank.

Actually, it is you who is mistaken.  The IFV was not derived from any tank.  The IFV is an evolution of the APC.

technology <> role

also, let me derail this conversation a bit further: why is everybody retiring their Broncos, Warthogs, BVS 10s? Surely if we want tracks, they are the way to go?

stancrist said:

Actually, it is you who is mistaken. The IFV was not derived from any tank. The IFV is an evolution of the APC.

I am not talking about what vehicles has wich linage. But about the concept. The IFV concept is not derived from the APC but from the needs of the tank.
Otherwise why create an IFV in the first place?

BTW the M113 and all its variants including the YPR-765/AIFV are tracked APCs. In the case of the latter armed with an autocannon.
If your argumet is that its called AIFV by the manufacturer I say: you can put lipstick on a swine...
It is true though that the AIFV was an attempt to adress the shortcomings of the pure M113 APC.
Never the less AIFV isn't the first. It was done after the IFV concept materialised in the form of the HS30 and the BMP-1. Neither of these two is an evolution of an APC.

graylion said:

why is everybody retiring their Broncos, Warthogs, BVS 10s?

Who is doing that?
The German Army is in the process to replace/supplement its BVs with the CATV. Wich is basically a follow up on the BV10S.
The CATV program is a multi national program from Germany, UK, Sweden and the Netherlands.
I have seen one of the prototypes during testing in Trier a couple of month ago.
Serveral of the vehicles you mention need to be replaced because they have been worn out by the long and intensive use in Afghanistan.

schnuersi said:

[The ability to keep up with the gun tanks across all terrains in all conditions at all times] is what defines the IFV and seperates it from the APC.

Nonsense.  There is no reason that an APC cannot have the same mobility as an IFV. 

Indeed, since an APC typically weighs significantly less, it can have better mobility. 

schnuersi said:

An IFV is a vehicle that can perform the combat function of infantry.

That is false.  No vehicle can perform the combat function of infantry.  That's why we still have infantry.

schnuersi said:

IFVs are all about mobility and firepower. Troop carrying is tertiary to this.

That's absurd.  The only reason that IFVs even exist is to carry infantry.

schnuersi said:

       stancrist said: When the Marines' decision makers disagree, "the Marines" disagree.

Well, is it clear that the wheeled ACV can move over all grounds at the same speed as the AAV then?

I don't know.  You would have to ask the Marines.

schnuersi said:

In the video it even says the APCs need to be backed up by tanks. In other words they are not supporting the tanks.

Well, duh.  It's an infantry assault.  The tanks are supporting the infantry.

schnuersi said:

The M113...can not operate close to tanks because its to slow, lacks protection and it doesn't really bring any mounted firepower. The only thing it brings is dismounts. And this rather slow I would add.

Depends upon which tanks you're talking about.  AFAIK, the M113 APC was just as fast as the M48 tank, and had equal, if not superior, cross-country mobility.

schnuersi said:

An M113 doesn't compare to a Marder or a Bradley.

Of course not.  The Marder and Bradley are later generations of armored infantry vehicles.

That is like saying the M1903 Springfield doesn't compare to the M1 Garand or FG42 rifles.

stancrist said:

Indeed, since an APC typically weighs significantly less, it can have better mobility.

Tactical mobility not technical. To have tactical mobility compared to a tank you adequate protection. A light weight APC lacks protection and thus its tactical mobility is significantly less compared to its technical mobility.
But of course there are some heavy APC that do that. So it is possible. Its just uncommon and a hAPC is not an IFV.

stancrist said:

That is false. No vehicle can perform the combat function of infantry. That's why we still have infantry.

Nope. It depends on the circumstances and environment. In combined arms manoeuver warfare vehicles not only can perform some combat functions of infantry they are needed to do so since infantry peforms poorly or isn't there.
There have been several attempts to dispense with dismounts entirely. With limited success until now. We will have to wait and see how the BMPT performs in UA.
This is also why mech infantry usually has significantly less infantrymen per unit than non mech infanty. They don't need them. Six men plus and IFV easily outperform a platoon of foot infantry in a lot of scenarios.
Most attempts with UGCV have the ultimate goal to replace infantry in most scenarios with the intermediate step of supplementing infantry.