Today, we switched from Snitz Forum to Community Server. The main reason for this switch was performance-related: the original forum has outgrown its backend database. We tried to postpone - or put off - that necessary step for long.
One reason was that I originally planned to migrate the data from Snitz to CS, but that turned out to be a rather nasty process (the schemas are way too different, not to speak of user profiles and password storage). So it was decided to leave the old forum up and running in read-only mode, and have all new posts in the new forum.