BuddyPress.org

Hopefully someone else will chime in, but the only thing you may lose by not importing the bb_usermeta would be any customisation a user has done to their “display name” or “nice name”; it’d default back to that person’s username. They’d have to just type their preferred display name back in to WordPress or bbPress, so nothing tricky. So, I don’t think you need to.. probably.

I get the feeling you’re aware of this, but I’d suggest having a test-run of this to find out how well it works (or doesn’t) before doing it on your live database. Also, check that bb_usermeta and wp_usermeta have the same columns, you may need to massage the import a bit.

Once you get the users into WordPress, and you can log in as one of them, we can see about associating existing bbPress forum posts with a particular BuddyPress Group’s forum. I’ve not done that myself so hopefully someone who has can guide.