I have talked to some people that own it on here. Everyone seems to like it. They say that there are some minor setbacks, but it will beat manfrotto tripods in that price range.
Im on a 701/055 set up right now. Next time I upgrade, I will most likely go for the FSB-4 with stock legs, or if I have some cash to spend, I might get the miller stage-2 legs that everyone loves. I havent really seen the point in upgrading to the ACE, then having to upgrade again.