In a Condor a few years ago, I did some experiments gliding engine off, prop windmilling and prop stopped, and the difference was only about 100ft/min worse with a windmilling prop. Try it. Also, even a Pitts will do a 180 turn back in 200ft, but I covered all this about two months ago. I am glad to see people actually investigatig what their aircraft will do. (At a safe ht, properly pre planned)