(update from my post a few days ago)
I seem to be fortunate to not have frequent glitches.... just one here and here, and so far, not one during video playback. Support has contacted many of us, and I was asked if I could provide a video of the issue. I was able to capture it on video, and I suspect others could too. Apple has my video, along with still photos of each phase of this glitch. For me, it's black, snow, lilac/purple, more snow, black again, normal video for about 1 second, black flash, DONE. The entire sequence lasts about 5 seconds.
One thing I noted, in my case, was I finally noted the exact time of the problem. There were no Console Log messages at this time. Previously I has guestimated the time of failure and saw video sync messages - but that was probably me switching inputs or resolutions.
yes - HTPC users beware. This is the first time I decied to be an early adopter..... of course there would be issues.
I'm not too keen on a new mac, and it seems replacements are not helping.