DVR Expander

In the last couple months I've been looking at DVR Expanders like this one and am wondering if anyone has any experience with them. My reasons for wanting one are two fold:

Reason the first. The most obvious reason is that the DVR I use is provided by the evil folks at Comcast and will hold 60 hours of standard definition programming, which is more than enough, but will only hold 15 hours of HD programming. That means if I record 2 football games, that fills up half the capacity. Not to mention the fact that I've gone on vacation and run into storage issues before. So the added capacity would be nice.

Reason the second. Since my DVR is provided by the evil Comcast, it is prone to the occasional demon possession episode. I have had it freeze up on me and reset itself, deleting the entire contents. Unwatched episodes of tv shows and movies gone forever. I also had another incident where it started recording an episode of Monk and then decided it was never going to stop. I woke up the next morning and found an 8+ hour episode of Monk still recording, deleting saved programs to make room. Having saved programs on the expander would keep them safe from a runaway DVR.

So I'm hoping that someone has some experience with one of these. Reading the user reviews it sounds like it's easy to set up and use, the one major concern for me however is compatibility. It says it has been tested for compatibility with Scientific Atlanta 8300 or 8300HD DVR, but my Comcast P.O.S. is made by Motorola. It does have an SATA port, so at least the expander could be plugged in. I've done a limited amount of googling on the subject and since it appears that Comcast uses different models of DVR, it's hard to find anyone who has tested the expander with my specific model (DCT3412 I). I refuse to call Comcast and spend 5 minutes wading through their automated menu just to get someone who either has no idea what I'm talking about, or at the very best will say that it might work but they can't make any guarantees. Although I already need to call them for another issue, so maybe I can just inquire while I already have them on the line. Anyone willing to save me the trouble and give me a definitive answer would be appreciated though.

In case you are curious, the other issue I have is that they mailed me a flyer back in December telling me I should have about 30 new HD channels (depending on the package) as of 12/19. So far I get none of these channels and trying to email them for a solution has proven quite unhelpful. I've gotten advice like, "make sure your connections aren't loose." Good lord, like that's the reason I don't get channel 517 but I get both 516 and 518. I simply haven't had the patience to talk to someone without getting angry about it yet. I think I may have anger management issues. Until Comcast foots the bills for therapy though, they aren't going away.