Very very nice cherub. I always miss your posts, not the better place to find them.
If you gonna use the BPR engine, go under material menu / environment, shades at ~80 . Then under BPR settings / shadows, rays at~ 40 or more and angle at ~10 . AO on as default.
Avoid using matcaps, they don't react well. Better construct a one or two nodes shader (in the case of two or more nodes, you have to enter environment shades for every node). Use a light cap, a second as RIM light at ~10-20 energy but use exposure slider at >5 - 10
Here's a small BPR tutorial LOL. Something that simulates a ray tracer. For better results, rim lights should be exported as multi bass layers in Ps. One light only in zb reacts like a ray tracer, have it in mind.
If you gonna use just the default settings, you get these wrong, pale casted shadows.