Mihai - your right - infinite light in MR, so it really isn't a fair comparison, but I think the
maps are behaving a bit differently between 32 and 16 bit... not sure how to make a more
direct comparison.
Here is another test. This is a slightly different, using just the physical sun and a reflector to his right.
He's is in a grey box with a couple holes cut out at the top to let in light from sun. Took about 2.5 hours to render.
I also changed the material - the previous renders used a single sided SSS on a different
layer, this is weighted BSDF on same layer. Not sure if that helped or hurt the render time or look of the
image (not enough experience yet).
EDIT: made the changes (adaptive off, etc.). The ZB file is exported at level 3 (~97kpolys) out of 6, so I've
subdiv'd him in MW 3 times for the following test... I'm guessing subdivs are the same.
I like this image and should have let it render longer, but I need to fix the eyebrows and touch up the hair.

Are there any .mxs files around that have good demonstration of material/lighting combinations used for skin? It
would be great if there were some scenes on think.maxwellrender.com.