I think not being right on the edge is better on flat areas, i say this because when your right on the edge when you kick hard on the pedals it shoots you down a bit, so on flat areas start a bit further back, on natural get right on the edge but dont kick down as hard on the pedals you need to be getting your ass down as far as possible and then explode up as you kick down, as if you were trying to jump the gap without the bike?