On the saddles...sometimes a gaited saddle does indeed fit a gaited horse better because of how the tree flares for freer shoulder movement, which in turns encourages a more correct gait. And the more correct the gait, the smoother the ride is.
How any one saddle fits seems to be based more on how the individual horse is made.
While I do not own a gaited saddle, I can tell you that because of how my RMH is put together, a typical western saddle doesn't fit him properly and it is part of why I have stuck with English and Aussie saddles.
He is wide, low withered, and extra short backed. However, he still needs a saddle that allows for his movements and that is near impossible in most western saddles... for his particular shape.