I don't want to keep beating dead horse, but...from what I understand anodizing is a process by which aluminum is forced to oxidize, forming this layer of anodizing. If this is true, then black type II anodizing may actually promote the dissipation of heat, while type III may inhibit it.

I just know that type III is some pretty tough stuff. I had a tube that I turned out of 6061 aluminum, then knurled with some pretty aggressive knurling and then had type III anodized black. Although the anodizing did nothing for the tensile strength of the aluminum (it would dent if I slammed it again a brick), I was able to saw into a piece of wrought iron with the knurling without damaging the coating.