Use email as Login instead of username

Generally, those type of extensions are fine to use with JFBConnect since they effect the Joomla-credentialed login, which we don't interfere with. JFBConnect also has an option to generate the username from the user's email address, so that you don't need an extra add-on... though setting the username to an email address can cause other problems, depending on how your site is used.

Either way, the best recommendation I can give is to test different settings or plugins to see what works best for you. If you run into any issues or have questions, just let me know.

Thanks,
Alex