So far seems to work ok here. It helps a lot to push the Min Roughness to 1.0, to get more of what would be expected from a negative light.
I understand the push on more realism and physically based rendering. Will make a feedback on that soon 
So far seems to work ok here. It helps a lot to push the Min Roughness to 1.0, to get more of what would be expected from a negative light.
I understand the push on more realism and physically based rendering. Will make a feedback on that soon