The only problem with 3 blade props is their scarcity. The difference in efficiency between 2 and 3 blades is less significant than the lack of props to try on your engine/model combination. So if you find a prop that would seem worth trying, try it, because there are very few 3 blade props to even try.

My Yak54 with it's OS61FX was clocked at 93mph the other day. It was behind it's favorite prop, one that won a 6-7 prop comparison a year ago, a Master Airscrew 12x6(3). That one also pulls vertical better than the other 2-bladers tested. Could there be a better 2 blade available? Yes, but there wasn't in the testing.