I changed this because I found M-x to be really really difficult to type. It may be my hands or my fingers, but I have a hard time doing that key sequence correctly. Apart from that I think that you're absolutely right. I shouldn't have advertised this as it will probably confuse users.
Well, there's nothing wrong with rebinding M-x; that key combination requires a lot of hand scrunching, which can get uncomfortable after a while. Nothing wrong with talking about it, either! I'd just recommend describing it in accord with the conventions for Emacs key sequences, is all.
