Craig is Catto. That's his name, Craig Catto. See: www.cattoprops.com
Give him a call. Phone number is on the website. It's easier to communicate with him by phone than by E-mail. At least that's my experience. He'll discuss your needs with you. Very nice person to do business with. I've met him and spoken with him at Calavaras County Airport, in the Sierra foothills in central California.
If I were involved with a RV-10, I'd be looking harder at some kind of consant speed prop, but it depends on how you will use the airplane. I live in the west. We have lots of high elevation airports and lots of high density altitude days. For good safety margins, you might want all the performance your engine can give you. If all your flying will be lower elevation with wide open spaces, a fixed pitch prop might be satifactory. Fixed pitch propellers are always a compromise. You give up performance on one end of the range to get it one the other end.
As for two blade vs three blade, two blades are slightly more efficient. Three blade props are a little quieter due to lower tip speeds. They are smaller diameter. For that reason, three blades will give you more ground clearance. Three blade props cost considerably more than two blades and are generally heavier. From where I sit, that about it in a nut shell.