I sent a better more detailed note to Bob, so Maybe we'll get a better answer.

But here's my thoughts. We know that the 550's put out much less torque then the CC motors. As they are a 2-pole motor, and their rotor has much less mass. But being a smaller diameter lower mass rotor, allows them to turn higher rpm's, with less cintrifugal loads.

So by using this equation of Torque x RPM's = hp = watts = amps x volts
we know that torque or rpm doesn't matter, they should draw the same power, either way, for the same speed. So it's really all about which way the motor does it most efficiently. Which is where the motor's ability of producing less torque, comes into play. For a 2000kv motor to be pushing the same speed as a 4000kv motor, it must make twice the torque. If making that much torque, is more inefficient, then running that rpm, which imo it will be, the higher kv motor will be cooler.