The problem isn't putting up new software, it's migrating all the old data/accounts/comments/posts/etc to it. There is no existing software which will do that unfortunately, though I have considered getting rid of all the other stuff and just moving to vBulletin. Meaning Amiga.org would be reduced to a -- very usable -- forum only type site.
I personally don't go looking at old threads so the most hassle I would see is registering again. Just keep this current xoopsh*t based Amiga.org in read only form for archive purposes (guess archive.amiga.org?) and move to something better. AO has a lot of history, but it's the current users that keep AO special, not it's old threads.
Dammy