I LOVE YOU REBB <3
Edit: Just tried on a more heavy-duty test case, this time a 350,000 triangle decimated mesh from ZBrush.
It took just over 90 seconds to calculate, which isn't too bad. I think the results would be better if the mesh wasn't run through decimation master, but obviously it'd take a lot longer to process. After doing Smooth a couple of times on the result I think it'd be good for most uses anyway.
My next step is to try hooking this up into a shading network to control material parameters through the red/green vertexcolor channels
Shame that Maya makes working with vertexcolor in Mental Ray such a total bitch.