I use Wishlist Member, a premium plugin, which is the bread and butter of my digital courses. And I use XF for specific membership levels to provide online support for the products they buy. So they buy through Wishlist and they get support through XF. But this means 2 accounts, 2 logins, etc. Very annoying and confusing for my clients.
Ideally people will create an account either in Wishlist after purchasing a course and then have automatic access to that same membership level in XF, or they create an account in XF (if they first land there) and then have access to commenting on posts in Wordpress.
If anyone is wishing for the same bridge - please tag along and let me know how you can help. If there is any developer out there able to create this add-0n for us, please comment or send me a PM.