Yeah, HV is definitely the way to go. What I did was this. I set everything up to go at a speed that I was happy with on 5S. I was getting around 52 mph, I think. Then I used Brian's calculator to figure out the gearing that I needed to go the same speed on 6S and voila. It's perfect.

My setup with the Compro is every bit as smooth as the Quark setup and the temps dropped. I don't think that I saw anything over 120 on the motor and 110 on the controller and that was after multiple full throttle runs down my street.

I think that I'm going to try a 16024 on a 1500kv (or less) motor. That way I can get a Maxamps 8S 4Ah pack, which will be the same physical size as a 4S2P 8Ah pack.