Considering some of your VRMs were over 100 degrees (based on pictures you posted earlier). I think you could safely say you achieved as high as 30 degree reduction on some VRMs. I think the VRMs and the fact that they are they are the BMR4641002 (max 40A) instead of the BMR4641008 (max 50A) as you mentioned earlier are the most disappointing aspect of the current design (KNC that's not a criticism; but a critique). I do understand that KNCminer was under a lot of pressure to ship before the end of the month. I wonder if they were expecting far greater power savings and that is why the board does not have the 1008s.
I think delivery dates written in stone are a two edged sword. They give targets to be achieved; but, can result in shipping before every important detail is fully dealt with. Hopefully we'll see revised boards coming.
I agree: KnC should have used more robust VRM's.
And indeed I had 107 degrees with some of the slot-1 VRM's due to a gap between pad and VRM... see this picture:
