RE: use 2 bladed prop to replace 3?
I use an 11x4, 5, 6 prop on one of mine. Start with a lower pitch, you will still be amazed at the speed difference. I too like the spinners with the aluminum backplates, they seem to fit more types of props. I tend to use Master Airscrew more than APC. It seems like I don't have to cut the spinners as much to fit. Good luck!