BuddyPress.org

It does not work to use a standalone forum because then you lose all the group making aspects of Buddypress.

You do not lose all group making aspects by using this approach.

You can use both BP group forums and your external version of bbPress at the same time.

There will be some duplication in your external version of bbPress. You’ll need to find a way to address this issue. One way is to hide the group forums in your external bbPress. I did a writeup on this a few weeks ago; I’ll provide the link to those who want to read it.