Welp, I found some time tonight to play and everything went pretty smoothly, though the fan from my budget Xigmatek Gaia gets right up next to the heat spreaders on my RAM. If I had gone with the Hyper 212+ Evo (1mm deeper) it wouldn't have cleared. I'm glad I measured beforehand.
Gotta love Windows 7; it handled the upgrade from LGA 775 to 1155 with grace. I didn't have to Sysprep, repair, or reinstall the OS. Just booted up and started updating chipset drivers. I also took the opportunity to install a little "catproofing", so hopefully I want have to clean out the dust bunnies as often.
The only hitch was in the UEFI. It doesn't like my RAT 9. It's erratic and it's impossible to move the cursor to the left. An older USB mouse worked just fine. I vaguely remember a similar anecdote an another modern motherboard review, with a different brand of "exotic" mouse. My friend noticed similar behavior with his RAT 7, testing it in the EFI of his Mac. I'll have to research this one of these days. It's not a major deal, but I'd love to know why.