I'm making a total guess here (I don't have the product, and have P6, not P7), but...

Are you sure you need a Texture_Strength of 1.5 for your reflection map?
Increasing the texture strength above 1.0 can produce weird colour effects. I'm not sure if that's true for a grey-scale image, but its worth trying a quick render with T_S set to 1.0.

Using IBL will tend to wash out/flatten the colours, so that maybe why it looked better.

Or, of course (and more likely), it has nothing to do with anything.

Cheers,
Diolma