I ran the 21x10 all summer. I really liked the pace (6300rpm) all around for the simpler maneuvers in the masters class. Doubt fai would like it. Been trying the 20.5x10 lately and am going to switch to it as it pulls over the top better then the 21 and pace seems to be about the same. A 21x10 at 6300 is getting close to electric numbers, just doesn't quite have the torque of electric. 185 may be perfect for it.

Weights of the apc's are at 6.1oz for the 20.5 and 21 x 10. 20x10 is 6.5oz, it's a narrower blade but a lot bigger hub.