That "+" is pretty subtle. I went to the web site & had a few boards lined up in the comparison tool & didn't get it.
We have talked before about the 2 oz Cu buried in the PCB as to what heat removal benefit it could be ... of which I am skeptical. But, it can't hurt in anyway and I do think with the current draw and other electrical performance issues it would be helpful.
Win 7 64 bit, ASUS X99-A, i7-5960X
G. Skill 64 GB RAM DDR4
NVIDIA Tesla M2090 + NVS 290, Seasonic X750
Koolance CPU-380I block, Indigo Extreme TIM
Swiftech MCR220-QP Radiator, Eheim 1040 pump, 1/2" ID Tubing