I really like the setup you prupose. Thanks for making it easier for us to gain the knowledge you have.
Just a question, i always thought that when you use translucency, the translucency color was the backside of the thin polygon? Why do you setup a front/back material than in the diffuse slot?
Or do i misinterpretthe front/back material?
Thanks!
Not sure I follow you correctly, but:
The front/back in Diffuse slot would be there even if the leaf wasn't translucent at all. That's not the color you see against the light, that's the physical color of that surface. Leaves have different surface on top (facing the sun) and the bottom of the leaf.
The translucency slot (back when I did this with version 1.0. there wasn't translucency level slot, only single one), influences what happens when the light travels through the leaf. It simulates the "inside" of the leaf, the so called subsurface scattering, and leaf looks the same against light/sun no matter which side you hold it against.
What you describe, is what happens with Vray2Sided shader, which imho is good only for simulating paper at best.
Transparency =/= Translucency.