Mediawiki is fantastic software, we'd be able to operate on a lot less hardware if it was just mediawiki, but because of the forum we had to boost everything up. For anyone who ever considers using phpbb for anything serious: please don't.
We're looking at a couple of alternatives and I can report back with our findings when we know enough, right now we're looking at vbulletin which powers some of the larger forums, it is apparently very good if you're willing to strip out the poor parts (apparently search is terrible).
It looks as if the best approach is to roll your own, phpbb seems to be designed with the smaller user in mind, so while routing every single file through file.php for easy processing might work well for Johnny and his friends forum, once you hit a large scale it becomes rather a pain.
So yeah, no idea, we'll find out soon though, I'll report back when I know :-)
