after 2 months of trying to get the Pro-Render settings,checking all the bryce threads on TA and anything related,I have to say that refraction does do something.But NOT in normal renders(at least to non-transparent objects).It does however seem to give diff effects with "VolumetricWorld" settings on,and or TA.I have to support PJF on his observations.I have recreated all of the experiments PJF did in the thread he just mentioned.And some things he hasnt said.For example, I made a sphere with a metal mat that had refraction at 100,and another at 300.The sphere at 300 reflected MORE TA light than the other(note: it will not do this if the sky is set up wrong).Which leads me to another obsevation, if your sky is set up in a certain manner, it can and will entirely change the scene,and the way mats look.

I eat babies.