Well, I've got the new cable box now, and I'm happy to report, all is well. There is occasionally a noticeable, but not annoying delay, which I think may correlate to channels that are PCM, rather than DD. On the flip side, there are occasionally situations when the audio begins before video even shows up!
For those interested, the new cable box is a Motorola DCT6412 Dual-Tuner DVR. I'm pretty happy with it on the whole. The reason I got cable was entirely for the HDTV, which it does very nicely. Compared to Tivo, the user interface leaves a lot to be desired, but if I never used Tivo, I might think it was pretty good.
One note about Tvio - though I've heard the Tivo may not be standards-friendly with its digital output, I have used it with a few receivers - Sony and Onkyo, specifically - and they had no problems with it. So, while I agree the Tivo may not be cooperating well with the other components, I know that others have managed to work around any idiosyncrasies.
I'm finding the Outlaw/HTM remote pretty liveable, and have programmed the menu navigation buttons for DVD and DVR into the listening mode buttons near the bottom. I still wish there were separate transfer and navigation buttons, but I'm not in a rush to replace it.
Lastly, I just finished watching the extended LOTR trilogy over the last week or so(1 disc per evening), and am as thrilled with the Outlaw's sound as when I first unpacked it. All-in-all, I think it's a great piece of equipment.