Nice topic. But obviously there aren't to many outthere.
Every guitarist wants to be one of a kind in his own right so I think that's the reason why no famous guitar player plays the signature of someone else. I'm sure enough guys own the stuff but nobody dares to play it on stage because he doesn't want to be called "wannabe-Keith" or "wannabe-Richie" or whatever.
I recently bought Brian May's Red Special. It's one hell of a guitar, pretty awesome for all kind of sounds. But except of Brian May himself I've never seen any other famous guitarist play this guitar in public.