IMHO, you are blasting your scene very intense lighting.  Is your IBL based on an image or is it plugged directly into your diffuse_value which would explain the 200%.  Your infinity light should carry the shadowing load of your image but if you are rendering with Gc, then there is really no need to light at 100% intensity.  And exactly what is your diffuse lighting?  IIRC there is only diffuse IBL in the properties panel.  Also which Poser are you using again?