Higher kv vs. taller gearing

So do you think my mamba would run cooler on 5s, even though its not rated for it? And is there an ESC that wouldnt make any heat? I thought even the $300 quarks had heat issues. Would an MGM run cooler?
Im going to upgrade to an HV setup in this buggy someday, Ive been wanting an MGM 9032 on 8-9s running a Neu. But now Im going to wait to see how the MMM does, since it sounds like thats going to be a lot cheaper.