there will always be example and experiances to prove both sides. One horse that has a shipwrecked mouth is an exception, not a rule. As a rule, gaited horses ride into the bit. Most use the bit as a balancing tool. Do they need it at all times, no b/c many can gait through the field, w/o human interferance, but you add a rider to the equation and a multitude of other variables and the bit is a strong aid to helping a horse gait and making the gait better, and smoother.
The video shows how a snaffle works, a gaited horse will have continual pressure on its mouth while its in a rack or other gaits, a snaffle and its design is not something you want continual pressure on the horses bars and palate. Not to mention the possiblity of the tounge and lip tissue. That's why im more in favor of a curb where pressure is used for gaited horses.
no doubt most if not all gaited breeds can go in a snaffle, I've used them before, a good rider can make a horse do anything. But that doesnt make it the best tool for the job. The snaffle may be a good tool for some and thier disicipline. But I don't care for them.............i rode TWHs and now I ride big motor speed racking horses.