I have the SA8300 (HD/DVR) and I got it about two months ago. When I first brought it home from the Bartlett Kroger office, it rebooted a lot and I couldn't get TNT HD at all. Also, ESPN HD came through with a lot of jerkiness and pixelation.
I placed a service call and a middle-aged tech (who seemed to be training a younger tech) that really knew his stuff traced it down to a couple of bad cable runs, which he replaced.
I was really glad, because a lesser skilled tech would have blamed it on my splitter/amp, which I paid a lot of money for and it just ticks me off when they try to use that excuse. He was quick to point out that it was a nice one (which was my first indication that he was not just another joe) and proceeded to methodically troubleshoot until the problem was fixed.
Kudos to TW, since now my box reboots so rarely that I can't remember the last time it did, and my HD ROCKS!
As far as whether TW currently has anymore 8300's, I don't know what to tell you. It is feasible that there was a run on them when ESPN HD came online.
Former Bose owner - Now Recovering with Klipsch Reference Series Therapy