I was doing club racing for a few years and we had a gent come in from another city near here to race with us. Most everyone was running the TT40 Pro but he was running a different brand. Not wanting to bring up engine types but rather prop differences I'll leave the brand out. He had tried everything APC made and was about to switch back to the TT40 when he decided to try a Master Airscrew on it. Needless to say he won the overall event and had done so at other events with that setup. The APC seemed to be the prop to use with the TT40 but not all engines like the same setup. I learned a lot that day and since I also was NOT running the TT40 I decided to try different props on my racer and found that indeed other brands can and do work very well. In fact, one setup worked best with an old style MA to the tune of about 3 mph on radar. (Ten runs averaged together some at 2 faster some 3 and some 4 but the average was 3) The engine was turning more rpm's on the ground with the MA and when an APC was selected that gave similar rpm the speed went back down. That's when I came to the conclusion that no one prop suites all applications. It really is all about trial and error. Some call it research and development in the racing world.