My preorder (technically my second preorder, see below) device was awesome, ran starving at 1000 Mhz and was very stable (my standard profile was 125-900 MHz starving).

Broke the USB connector (luckily still under warranty) and the best the replacement device can do at default voltage is 805 mhz. Lowest I can go is ULV. Now I run 125-700Mhz ulv. Pathetic.

I was spoiled I guess, I can barely stand the slower speed now. Smart reflex for battery savings is all that keeps me sane.

So my experience is that preorder devices were MUCH more stable at high speed and low voltages.

(Note, my preorder device was actually my second device as the first one had random reboots from the factory and was replaces ~ 1 month after release)