Having been all around the houses, had treeless - Freeform, HM Vogue and Barefoot - am back to square one with a treed. And I am happy with it, and more importantly, so is Tobes.
Personally (ducks to avoid poison arrows!), I don't think you can get better than a properly fitted treed saddle. Freeform rubbed him and slipped, Vogue gave him raised lumps under the stirrup bars, and Barefoot gave him a swollen wither on one side. The reason I went down this route was because the treed saddle I had at the time caused him to buck. Actually so did the treeless saddles, so it clearly wasn't a saddle issue, although I am not convinced that the treed saddle I initially bought him was fitted correctly.
Guess it is horses for courses, but actually, I wouldn't touch that roller/surcingle with a very long barge pole.
Is bareback not an option?