The coonhounds are FSS because the AKC runs coonhunts. The reason the Black and Tan (and now the Plott) are registered both ways is that the bloodstock is completely different, like many AKC breeds, regular AKC Black and Tans are really now useless for their original purpose, they are much heavier than "real" coonhounds, for example. Far from being some kind of designer dogs, these six breeds are real working strains of dogs that have been around for a couple hundred years.
There are several other registries (UKC, PKC) that register coonhounds and run both hunts and bench shows. Beautiful dogs, mine is amazing.
He is beautiful, inside and out.