I see reading the earlier post that the 50sx is marginal at best. the saito 72 would work but I don't see you having any reserve on pulling out of a hover. I think the 91 or 100 would be the ticket. My 91 is not too much at all I say just about perfect. With a 4 inch pitch prop speed is not a problem and you have pull out of the hover. If your really good maybe you don't need the extra pull but at my level I sometimes need the power to get out of trouble. The Weight differance is not much of an issue with the extra power and the little amount we are talking about.