Ok, I've now been using the Comcast/Motorola DCT6412 and I have quite a few comments/problems, so I thought I'd share them here. First, let me say that, although there are some issues I'll note below, the software is decent. I have some issues with the hardware though.
--- Hardware ---
1) Am I the only one who finds the hard-drive accesses to be extremely loud? I actually returned my first DVR box and got another one because it annoyed me so much. The new box I have is better in that the hard drive isn't too annoying when the box is "off", but when watching shows I can usually hear the hard drive over the TV, which is not a good thing. Despite the other problems I list below, this one is the deal breaker for me. If I can't get a quieter unit, I'll probably cancel my DVR service by next week. I'm surprised no one else has even mentioned the noise, but perhaps I'm overly sensitive.
2) It is a bit annoying that Comcast "ran out" of the DVR remotes. They're mostly just giving out the normal remotes without the Instant Replay, My DVR, and Live buttons and they are telling me it will likely be months before they get more in stock. I am at a loss for how they can have so many more boxes than remotes, but oh well.
3) On the Comcast and Motorola sites, they state that the 120 GB drive should be able to store 90 hours of SD TV. Well, I now have 4 hours of SD TV recorded and my capacity is at 12%. This gives me about 30 hours total, which is a fraction of what they state. Is anyone else noticing this?
4) What does the Record LED on the front of the DVR box do? I've tried recording shows while I'm watching them, scheduling shows, watching shows live while recording on another channel/tuner, and this LED never turns on. Is this just not implemented yet? None of the manuals I've found mention the "Record" option. They all state that there is an A/B Bypass there, which now exists in the box options menu.
--- Software ----
5) Earlier today, I was watching channel 4 (KOMO) at 7:30 and had a show scheduled to record on channel 10 (WB) at 8:00 PM. At 7:59, a dialog came up warning me that my show might be interrupted and asking me to switch to channel 10. Why would it do this?? Isn't the point of a dual tuner to be able to record and not have to watch it also?
6) Similarly, tonight as well, I was recording on channel 10 (WB) until 10:00 PM and had a show scheduled to start at 10:00 PM on channel 5 (NBC). At 9:59, a dialog came up telling me to switch to channel 5 or cancel the recording of the show on channel 5 at 10:00 PM. Again, why is this necessary? Shouldn't I be able to stay on the channel I'm on and still record this?
7) The Mini-Guide is nice, but I must say I do miss the easy little "up-arrow" I could press on my old digital cable box to see the current program. I could then press the right arrow to see shows coming up next or type a channel number in and see what was on on that channel. I can sort of do this with the Mini-Guide, but the "Mini" guide takes up half my screen while the old box could do this using only a fraction of the display. It's not a huge deal, but I used this feature quite often and am sad to see it go away.
8) On i-Channels I noticed that the titles in the Other Stories sections are cut off after only four or five characters on everything but the Home page. The Home page displays fine, but, on the others, the story titles are virtually unreadable. I don't really use this feature, but I thought I'd point it out in case someone planned on fixing it.
9) I find the Search to be hard-to-use due to the huge amount of text that's cut-off on the returned shows/movie titles. I can scroll over every movie to see the full title, but it'd be nice to see at least half of the title in the search results. I suspect this is Comcast's advertising and not the software, but it still is sad.
10) Finally, as others have said, the Menu navigation is very unwieldy. Pressing Last sometimes goes backwards and it sometimes changes channels. It's very difficult to determine how to go back one level of the menu depending on where you are.
Ok, that's it for now. If anyone read this far, I'm impressed.