I ran a 12X6 GWS SF and an 11X4.7 GWS SF on the 2212/34. I also did a little mod to a 12X6 to try to keep it 12" diameter but a little less load. The plane flew, and would hover, etc., just not over the top power like from a flat foamy/ Razor~Himax combo.

Alfster had a 2212/34 on a GW Yak this weekend, nice power, but still not like a Razor 350/ GWS D gear. I really don't think you will want to be over 13 oz with a 2212/34.

The plane Pauly posted used a 12X6 APC SF, 60 oz or so of thrust.