Commercial mail from St. Vincent is not commonly found. One dealer I am acquainted with has access to such mail, and I have looked through his offerings at stamp shows over the years.
A census of inland commercial mail that he receives suggests that only one or two basic definitive stamps are consistently being used. None of the few hundred covers he had on hand were franked with the many topical stamps printed by IGPC. One of the reasons these stamps are not being used is that IGPC tends to not make denominations available that pay basic inland rates. Higher denominations are printed to market to collectors, not to satisfy postal needs on the island.
Further, it is my understanding that Scott editors struggle with the problem of whether or not to list St. Vincent new issues. Their argument (and it's a good one) - if the stamps can't be found or are not being used in the country of origin, why should they be listed?
I, for one, would like to know IGPC's thoughts on the this matter.
Richard L. Beecher