I finally got around to playing with BPR especially since R2b has hair. Yay!!! Thanks Pixologic, now I can finish projects requiring hair without having to shell out $3000 to upgrade to XSI advanced. The image below was done almost entirely in Zbrush. I did use uvlayout and body paint to clean up uv seams as well the final image was composited in photoshop. There does seem to be some issues with subpixel accuracy (despite setting subpix to the maximum 7) as seen on some parts of the hair but compared to mental ray, it's considerably faster. Average render time was 10 mins.
For comparison, this is something I did last summer which was sculpted in zbrush, of course, and rendered with mental ray. Average render time was, if I recall correctly, about 45 mins.