I used a APC 15x6 and it seemed just fine, although I didn't tach it. Lifted off (in a light headwind) after a 10 foot roll-out, so it ain't lacking for pull!

I have read that others are using 15x7 and 15x8, which I may try later after getting some more run time on the engine. This plane is pretty draggy so it seems lower pitch is probably better.