MANY gaited horses that come from breeders are on short or long shanked bits. Personally, I have seen very few on snaffles. But I have noticed, (at least in my area) many of the gaited horse clinicians won't let you be in their clinic unless your horse is on a snaffle!
My horse hated bits; all bits. So, I tried a very gentle hackamore (wide soft leather; very little pressure) and he calmed right down. Now I can also use a bitless bridle (Dr. Cook style model). A trainer who rides my horse when I am not home uses a soft rubber snaffle bit that is apple flavored. That seems to be the only bit he will tolerate; I think it is the apple!
I am just curious.... what works best for you?