If there's anyone out there with stamped dropouts and an adapter claw derailleur hanger, you can put whatever derailleur you want on it and it will work fine. There would be exceptions, but there are always exceptions. It's a non-issue. And if you don't already have an adapter claw, you can get them at places like this:
http://www.loosescrews.com/index.cgi...d=691710110644