I would also be interested to migrate our account just so the login would be easy.

That or stop hiding my login behind multiple clicks?! I don't understand why you would alienate your long-term users by making them click through unintuitive buttons.

Or if you want to not confuse new users, set a long-term cookie on my machine that indicates I'm a legacy user and provide the OAuth login by default in that case and hide it behind the link otherwise?