RE: DA50 RPM's
In the long run it's good to ahve a few props on hand, because each will feel different on a different airframe with the same engine.
However, based on your numbers wiht the 22x10... I'd stick with the 22x8.. ti is far and away the most popular prop size out there...
If you can get MSC, they are nice, powerful and a few $$$ less than Mejzlik...