I've been using wp-fb-connect with the majority of users registering this way. I'd like to switch to the WPMUDEV Ultimate Facebook because it really kicks ass.
I'm afraid that users will either not be able to log in or will lose their existing user names, not to mention some confusion when they get a confirmation request.
Any idea what I should expect if I switch this over? I really don't have the time to invest in doing a test site or anything but may have to do that to learn the repercussions. Just wondering if anyone here has done this and what the results were...