Looks pretty good to me, frankly I'm surprised! Diligence and all that...

As far as leaves go, why not transmapped planes? Just make sure to have your diffuse textures against a sympathetic color in the image or the transmap will show a fringe of that color... a white fringe if white is the background color. I dont see why strategically placed smart prop leaves wouldn't work, plus it will add some dimensional variety and realism.

_edit. oh, and don't overdo it with the bump settings on the leaves... High bump settings on leaves looks horrible IMO.