Well in about a week and a half, Patch Tuesday arrives sans any updates for Windows 8 (as support ran out for the OS on the 12th of January). So after running System Restore, I will be running WSUS Offline and downloading February's updates for Server 2012. I'll check the bulletins for each patch and see which of the patches do not relate to server-specific code, and attempt running those.
If my system updates successfully, great. I have unofficial support. If not and my system barfs, then I'll return to the last restore point. Then I'll decide if I stay with Windows 8, or go back to Windows Vista for another year (after all, my taxes will be done and I won't need any newer OS for another year.)
I'll keep you posted on what happens. I may need to patch/edit the update.inf file somehow, but I'm not sure yet. This will be the first time that a Windows NT 6x based OS runs out of support, to try this experiment, so I'm eager to see what happens.