I just got back from vacation last week and was planning to take a stab at migrating the stuff over this week.
No promises though, as for some reason I am having a bug that is causing the twist value to be incorrect causing a seam between all branches. I had fixed that bug at one point so I am not sure why it crept back in.
re: WorldPosition vs Z offset.
The worldpostion would be the incoming worldposition minus the Zoffset times the VertexNormal.
So OffsetWorldPos = StartWorldpos - (Zoffset * vertexnormal)
And yes, material optimizations were in 4.11.