Sgt_Kickaxe - 3:46 pm on Dec 14, 2011 (gmt 0)
I upgraded a couple of live sites. Nothing broke.
Are you sure? Just because a page loads and looks as it did before doesn't mean its code hasn't significantly changed, which may very well cause it to change rank in serps.
Do your pages look the same when viewing source ?
I'm constantly having to spend several hours after any update making changes to remove bloat and other junk, default installs are ok but can be made soooo much faster/better with a little effort (which gets undone in any upgrade).