Ok so I scaled up the shadows (just to look at them) and there is actually semi transparency, but it doesn't seem to be read the same as a image map (there is less semi transparency of grays than the image map) but the reason it just looks so wrong is the shadow darkness, with proc colours the absolute shadow darkness is near black.
Attempting a secondary colour adjust to change white level, see if this helps.
Ehh... Do to to the fact the semi-transparency falloff is so short with proc colours, I can't adjust the white level without it all just going completely transparent. So either get hard black shadows or none. Actually, this is possibly just takes playing decimal places.
Sorry for bother you Matt!! The difference in colour interaction through me through a loop.