I have a SP128 and installed 8.1 preview when in came out. Pretty smooth in my case. Then last month when Enterprise 8.1 Preview came out I installed that. A little less smooth, but none-the-less the OS worked fine. Then, like Endorsay, everything started failing at once - probably 30 days after install: limited connections, then not, then limited; freeze ups that only a restart would cure, then only a power off, start would work, then evew3n full power on would not turn on my SP. I did get a "beep code" like light flashing just inside the case by the power on button and always the same flash sequence (long, 3 short, 1 short, 4 short, one short, repeat). So I bit the bullet and reloaded 8.0 from scratch, I even did a kill disk to wipe EVERYTHING to DOD standards. The Win 8 Pro (x64) went on from a MSDN download direct to the boot and everything went smoothly.
On reflection, the difference that I saw between the preview versions and the standard, was not in the OS which seemed stable, but in the "preview" drivers which did not seem stable. I will now wait patiently for 8.1 official release along with the drivers (especially the Avastar350 wlan, firmware and chipset drivers). I know I took a risk when I installed the preview versions and I knew full well that the drivers in particular would be problematic. That said, it would appear that the Marvell Avastar 350n driver for 8.1 whose driver number I cannot recall but know that its third set of numbers in a series that is 14.xxx.yZZZZ, y=2. That driver is not ready for prime time.
But now all is well and my SP is humming along flawlessly. The good thing for me is that all of my stuff is saved to SkyDrive and more importantly to the 64 GB SDXC. I lost no data or apps, just a little bit of time. oh, a great lesson about beta products. On the other hand, I will still install MS beta products....what can I say, I am addicted. Sigh