A question to the board coders, since there was a lot of problems resolved, solutions, workarounds, plugins tons of material over the last three months, can you possibly just pull the posts and entries over, ignore the user and put in some random default so the posts and threads are still inexistance and not lost to the four corners of a round room?
I had a similar problem recently when porting one Forum script over to bbpress. The forum that was used allowed for guests and unregistered posters, but bbpress (as you know, you guys wrote it) doesnt. So instead of loosing the posts for the random walk ins I assigned a posterID in the bb_posts table to 0 so that post now shows as "unregistered", and if a guest created the topic I assigned the topic_poster in bb_topics 0 but left the name topic_poster_name.
I am sure you know all about this, and I am sure this wouldnt be easy with thousands of posts (I know how much work it was for me on the <small>small</small> board I ported over). But since this is the internets and all of us are all experts in our own heads I thougth I would throw my 2cents in.
On the plus side, I did have several pages of User Activity and threads created, and if I do say so myself alot of those were some real stinkers and very dumb kinda glad I can have some of my past cleaned up!
blah blah blah.