Just a heads up that I know of at least 2 F12 show stoppers (as far as
upgrading goes) wherein the computer screen doesn't display the session
properly.
https://bugzilla.redhat.com/show_bug.cgi?id=529128
https://bugzilla.redhat.com/show_bug.cgi?id=528188
Both of these cases involve NON proprietary display drivers.
If you Google a bit you might find other cases that involve non
proprietary and proprietary drivers.
Long explanation short, I would run F12 live before I did a blind
upgrade to make sure that the video display is going to operate properly
once you do upgrade.
Hope this helps someone.