PablowTwo != "fedora expert" ("!=" equals "does not equal")
Realistically, no. Also depends on what your definition of "anything" is in this context.
Backup all of your personal data that you want to "keep", including things like folder ~/.mozilla, ~/.thunderbird (so you can restore your firefox and mail settings later). Take your time in determining what you don't want to lose, because if you didn't back it up, it'll be gone forever.
Wipe out your F12 install and do a clean new install of F16 or F17. Then restore your backed up data to the new OS. In my opinion, any other path attempting to "upgrade" F12 > F16/17 will only end in disaster.