Oh. Thanks for giving it thought :)

It is really really cool what you have done here! I never would have thought such a thing possible.

I had figured it might be possible to add dirt as an edge_blender thing... lately I have put edge_blender on my IBL lights to darken the edges/crevases and that is going really well. I once tried to use the edge_blender to get a look like stippled shading for a"hand  drawn" look but it didn't work out.