It's possible, but not in any feasible way. You would need to downgrade all of the packages you have installed, most likely individually and by force over several hours (days?) of heartbreak.
Actually let's just say no
If you are going completely clean and redoing your partitions it's handy to keep a seperate root partition from /home as you can then image it before doing any upgrades. Check out Partimage for information, it's quick and can get you out of lots of trouble. Of course it's a bit scary if you aren't comfortable with partition layouts.