The Channel Master DVR+ has a nice program guide. Once populated, it looks forward two weeks. It records two programs at a time and can play/pause either of these programs during recording. If no recording is scheduled, pressing pause while watching a channel results in buffering up to two hours of material for that channel. This is convenient for grabbing a snack, answering the phone, etc.
I added a splitter to feed both the TV and DVR+ so I can watch a third channel while recording two on the DVR+. Picture quality is excellent.
I am using a 1TB HDD I had laying around. I think it is a Samsung F1, but I am not certain without looking. If I remember correctly, I read that 1TB will hold up to 160 hours. Color programming, as one would expect, appears to take more space than black and white.
I will say that my unit had an issue rendering it unable to boot. It was repaired under warranty. The first sign of the problem was when it froze during playback of a recording. Now that it has been repaired, I have had it freeze again. I have not had time to investigate, but it may be that the hard disk is at fault rather than the DVR+.
It isn't perfect, but it beats a VCR, is less expensive than Tivo, and is free of monthly fees. One down side is that the current firmware doesn't permit recording "all programs with the same name" on a fixed channel. It will record programs with that name on any channel. For example, locally This Old House airs Saturday on 8.1. The same episode airs again Sunday on 8.2. The DVR+ records both episodes, wasting HDD space and my time deleting the copy. Hopefully this will be corrected in a future update.
There is an informative Channel Master DVR+ Owners Thread on avsforum.
I tried the MythTV route and had issues getting it configured. In the end, I realized that if it took that much time for me to configure and maintain, it would likely be a bigger problem for others in the house. I'm sure it has its advantages, but at some point I get tires of fooling with things and just want them to work.
Todd