Our vBulletin 5 community was recently restored as a 1st anniversary celebration and we used the opportunity to gauge which the community prefers to use. Whereas we know the original vBulletin 5 software had the most initial members, a lot of them were lost in translation during our switch to vBulletin 4. This is another reason why we gave this chance for them to be able to speak up concerning any problems on the software they were already registered on.
The remaining community has plainly adjusted to vBulletin 4 which is a lot more stable and allows additional features to be added (such as the arcade and store). As such, the vBulletin 5 restoration had a very poor turn-out so has been taken down to maximise backup space (as vBulletin 5 is a BIG space hog and vBulletin 4 is not).
The vBulletin 5 forums had a notice to backup anything you wanted to keep prior to October 1st. Additionally they were restored for a while some time ago on an archive basis so people could look/backup their important data. So we trust that everyone who had stuff they wanted to keep managed to do so.
We remain now on the vBulletin 4 community.
Thanks for your interest in this matter!