mach1- Not sure myself yet? I will be installing a PST 600 very soon in my MB339. Tam has said his one flies great at 21 lb with the RAM500 + smoke, and is quite quick.... Slow end should be very good if AUW is kept down. It has a ton of wing area + big flaps, so I am not worried about landings. I hope to fly it off grass as well. : )