[deleted] I have only done limited testing on that side, but the extension is designed to be used just like any social provider (unless you enable the Wordpress only feature). Wordpress also matches existing users based on email.
Just keep in mind that if you login or register from social or email, the logic for new Wordpress accounts (username generation and welcome message) won't run, even if the email exists in the Wordpress database. You need to connect at least once from Wordpress to link the user, and global login only works if you login via the Wordpress Login button.
Once a user is linked with a Wordpress account, it's no longer possible to connect to it via the email login (an error message will let the user know if they try). However it's probably still possible to log into a Wordpress-linked account via another social login. The global login won't happen in that case.
