(Wait, so if I hadn't voted mine, you did?
)
First off: the content will be the same anyway (in the end); same users, same content.
Let me ask you something: Can you export all the wiki data?
Because DokuWiki saves everything as a text file; we can go in and get it even if bandwidth is exceeded or anything.. and can easily be moved to another host.
From what I hear from you (you can set permissions, etc.) you already have a back-end of some kind. Why not just take on the files too? There's no real maintainance to be done there. It's really not complicated. If we where to code the wiki ourselves, then we'd be screwed, but this software is
made to be easy.
If only my hosting account got validated real quick and I could show you how awesome it is
Sure, bandwidth is a potential issue; but I do think the small OP community won't exceed 10GB (a month?)