Should a 10xl on 5s run cooler that a 9xl on 4s?

If they're geared for the same top speed, I would think the 10xl 5s would be quite a bit more efficient than the 9xl on 4s, resulting in lower temps. That's just my gut feeling though, since I've never ran a 10xl before. My 9xl on 4s runs too warm for my taste, and I've been thinking along the same lines as you.

J.