Not sure, I'll test that at Aiyon when I'm home.
EDIT: Actually, that was never an admin CP feature, now that I think about it - I think Cid's just disallowed remote linking completely at EoFF. If that's the case, it shouldn't be any trouble. However, we'll need to pull a downtime to get it done, and keep in mind that while it will probably cut the database by (at a guess) around half, if not more, there is the possibility that it won't affect the overall speed of the forums. I'm not really sure how attachments in the database works, only that I never liked the idea of it (the only time I'd use it is if I wanted to back up every single part of the forums on a single database file for some kind of reason, but even then you can just download the images via FTP and then zip 'em). I'm not sure how long it will take as EoFF is bloody big, however it is definitely a simple process.
