Quote - > Quote - Some figure materials are setup to use the ALT_DIFFUSE channel and set the diffuse channel to a 0 value.

Why do they do this?  Is there a benefit to using ALT_DIFFUSE?  Seems like this happens after EZSkin is applied as well...

The ALT_DIFFUSE channel does not alter its input, it directly transfers it. The diffuse channel takes light and other matters into account. In the nodesetup which plugs into the AltDiffuse, this is already accomplished in the other nodes (and you don't want to apply the light twice!)