Most of the F3A guys I fly with use a tray and fly thumb and forefinger. They rest their hands on the tray and they really do have great control. I never could get used to it (maybe I did not try hard enough) so I stick with my strap. I find that body english often defeates the purpose, but when I concentrate on keeping my transmitter at the bottom of the strap and not using my body to make manuevers my flying improves drastically. For F3A I stand basically like a statue, the only thing moving is my eyes and head and the strap helps me greatly with posture.

Mark