After 9 years on vBulletin (up to 3.8.x), we decided it was time to upgrade our forums.
With vBulletin 5 being an epic failure and XenForo 1.2 available the choice was easy enough.
Took a bit of extra work because our main site's content is pulled from the forum database, so we had to adjust our external scripts, which worked surprisingly well.
Currently ~60k users and ~3M posts. 30 addons installed on the new XenForo install.
Some minor changes to the style coming, too, people complain it's too bright.
There are still a few addons that I need to write, but things are looking smooth now.