Hey, Oshyan et al -
I never was able to get entirely satisfactory results with the terrain I was working with earlier (heavily displaced procedural, with the local surface at large negative elevation). I was never able to get the grass blades on scale, have them sit on the terrain and match up with their shadows all at the same time. Something or other was always wrong, and there seemed to be, under those conditions, anyway, a completely non-intuitive connection between vertical offset, scale, and where the grass actually appeared. I even tried adjusting the displacement offset so the local terrain was close to zero elevation, but no luck.
This afternoon I created a hieghtfield-based terrain, applied some surface shaders, set up the grass clumps and voila! perfect. I feel better, but I wish I could figure out how to get it to work on the first terrain. I'll probably keep plugging at it.