I agree that the motor seems to be built for a larger lower RPM setup versus the smaller higher pitch. i dealt with this in a Dualsky motor which I am still running, I got good performance out of a 20X15 but noticed areas where the setup was lacking the power I wanted. I narrowed this down to the motor loading up on uplines and unable to maintain pulling power. Going to the larger 22X12 allows the motor to work properly in its power curve.

Good luck with the motor, if you are a pilot who flys at a slower pace than most, you will do just fine, and be patient in the wind.

Chuck