Hey matt,
i've tried with layered shader, and rendering time doubled, and now i just copied main shape and scale it for 0.001, and then applied transparent map, render time is back from "way to slow" to "bit better then way to slow"=)
Now i'll try to draw hi.. medium resolution bump map or find some references that may help... update after progress..

edit... i had luck with bump mapping, and now batch rendering... hope it'll be finished till morning so i can update

enjoy yourselves..