[reeper]

I actually just called both companies.

SCT: The guy a spoke with didn't see that knowledgeable but wasn't sure if GM would be able to see the flash-counts or not. But felt if your programmed back to stick you'd be fine. I left the call with not a high-level of confidence.

Diablo: This gentleman stated they froze the flash-counter for their flashes and GM would only see their flashes to the PCM. This guy seemed a bit more knowledgeable and I left the call with a bit more enthusiasm for this device.

Update:
I actually went a step further and contacted a few of the retailers on this board. All were up-front and indicated if your going to tune there will always be some tell-tale sign of it. Whether its legitimate proof is always up for debate. The other noteworthy thing worth mentioning was that most tuners indicated non-significant performance gains with canned-tunes and was more about throttle response and shift-points. So right now I'm leaning towards neither the SCT or Diablo. IF and when I'm ready to tune I'll prolly do the HP Tuner route with flex-fuel as that sounds like a more significant gain.