Jigoro Kano had menkyo in three styles of jujutsu before he created judo and he was consistently beating his teachers in randori through the principles he personally discovered and applied to their arts.
Actually, I can't find Kano's levels in the other systems. He may not have had three menkyo, though I've heard that before...
Here's a good article on the creation of judo, though. If anyone around here has this kind of experience, I'd like to meet them.