[eluser]Myles Wakeham[/eluser]
I hope you don't take this the wrong way, but I'm still trying to come to grips with WHY you would write this when there are lots of open source solutions (ie. PHPBB, etc.) that are already available. I say this with about 10 yrs of moderating forums experience.
Although I like the idea of forums written on CI, there are a lot of business issues associated with running a forum with the vast majority being security and hacker proof forum design. I've run vBulletin and phpBB before, and had forums routinely hacked by malicious users. The only thing that saved my sanity with this is that the phpBB community are fast to respond to any vulnerability, which allowed me to update quickly and avoid this. If you have a proprietary forum, then I guess you are not as much a target for attack. However if you do produce anything with some vulnerability in there, then you will be lacking the sheer community size that phpBB has to address and shore it up.
That, coupled with the huge amount of functionality, add-ins, skinning, moderator functionality, etc. that is already out there in other open source solutions, and I'm still trying to get my head around why the wheel needs to be reinvented here.