Yeeps, I think the value for the KA is different. This might be a bug I'd have to do some more tests, but it looks like the KA value on the skin node needs to be trippled. It may have something to do with the way the P6 handles "real" values and the thickness setting too. P.S. I'd use a diffuse node between the skin and the AltDiffuse root. I think that's why you are getting strange shadow behavior.