Setters are the ultimate in grouse dogs. Sure other breeds can find some grouse when hunted on them regularly, but a setter with a bell is the standard that all other dogs are measured in teh grouse woods.
I high;y recommend finding some local breeders that grouse hunt. Go visit them and get a feel for how their dogs hunt. Pick a breeder that has dogs hunting how you want to hunt and get a pup. If they do training there as well, all the better.
Buy the breeder, not the breed. It's better in the end.