Depends on how you perform the upgrade. I'd recommend backing up what you have and just trygit stash git pull git stash apply
It should probably just work, but you may get "merge conflicts" that you'll have to resolve.
What happens to the old posts etc. I've got a member on my forum that has changed his username a few times and deleted a lot of his old posts, however he now can't seem to find any from his old username. Are they piled into the UID of 0 range? As it says he still has 450 posts, but only posts/topics as his current username appear and searching doesn't seem to find much.
As it says he still has 450 posts, but only posts/topics as his current username appear and searching doesn't seem to find much
can you PM us a link to his user profile? sounds like a bug, but as @baris says, all posts are tied to UID so changing username won't make a diff, but possible something else (deleting posts?) could affect that. Tried fooling around a bit on my dev env, couldn't repro so I don't really know.