Sadly, I have not allocated the time to upgrade from F12 to F13. However, I attended the somewhat belated Toronto Fedora 13 Release Party hosted at the York University campus. Mostly this was a chance to catch up with some of the Toronto Fedora folks that I had met last year at FUDCon Toronto but I hadn't talked to in a while due an extremely busy personal life since the turn of the calendar.
I also got talking with Tom Fitzsimmons about version-to-version upgrades of Fedora. He does pre-upgrade every time because he likes his stable environment. Andrew Overholt had just done a DVD upgrade to his laptop. We got discussing the merits of keeping all of your existing install versus starting fresh with a clean wipe. I hadn't quite realized how novel my approach seemed to be, so I figured I would share.
On my main desktop, I have a 200 GB hard drive partitioned thusly: 200 MB for /boot, 2048 MB for swap, the rest is an LVM partition. In the LVM Volume Group, I've got a 20 GB LV for my root partition and a 40 GB LV for my home directory. Various other LV's are created usually for virtual machines.
When I want to install a new version of Fedora, I create a pair of new blank LV's for my root and home partitions. These are side-by-side with my existing active pair. I then download the DVD iso, burn it, and reboot into the installer. When I get to the storage section of the installer, I select manual partitioning. It automatically detects my existing LVM partition and lets me manipulate it. I let the installer obliterate my /boot (I find it is unhappy if I do not let it own /boot) and point it to format the blank LV's. From there, I proceed as normal with a fresh install. I really should figure out a better way to do the package list, but I typically pre-select most of the stuff I know I'm going to want. Once the install completes, I reboot. I now have a fresh install, and my old install is still available for reference purposes to grab configurations, customizations, and home directory preferences. I copy over everything I want to save from the old install, then leave it around dormant just in case I have forgotten something. If/when I get to the next upgrade without using the old install, I can reclaim the space for the upgrade. In a pinch, I can also rescue boot into the old install.
For me, I mostly end up with the best of both worlds. On the one hand, I get all the bells, whistles, and default configuration of a fresh install. On the other hand, I also get an easy migration path to get my old data onto my shiny new install. This is clearly a little bit more work than either pre-upgrade or a clean wipe, but I find it worthwhile.
Does anyone else use a similar procedure?