I do keep /home on a separate partition, though, so I don't lose my data.
This laptop is brand new, though. It came with W7, so I reconfigured the HW RAID to mirror rather than striped, and threw F15 on there. It's been a very rewarding experience, with no issues for me at all.
This time round I have separate partition for /home as well, but - there is a lot of time and effort spent in downloading software and configuring software. I guess I have my yum logs and I could “replay” all the yum installs into a new distro - but still - a working installation is more than just data in /home and what you get out of the box. Even trivial stuff like fonts to more major stuff like server configs and as I said, installed software. I think best to not go through that every 6 months if not necessary. Also maybe this will allow them to work out the gnome3 issues.
On my last machine, I actually performed a “preupgrade” from F12 to F14. Worked very smoothly. That was the only time I have not done a clean install.