Re: Existing bbpress to buddypress
I’d just go into the MySQL database for the old one with PHPMyAdmin or whatever tool you use for a MySQL GUI and export table by table, then import to the corresponding bbPress tables in Buddypress. You’ll need to hand-edit some stuff in the meta tables and generally mess around, but I’ve done it a few times on my testbed and it’s worked just fine.
Set up a testbed BP install first and populate it with some test data to see how things fit together — it’s not all that complicated. Then try the export-import process on some test installs, figure out what needs to be done. Basically, now that I thought to look at it, what Boone talks about in the post r-a-y linked.