After reading most of this long thread and being aware of the problems many people have had, I decided to go ahead anyway and buy an open-box DHG-HDD250 unit from BB for a good price (though more than the tweeter.com deal). Fortunately, my TV Guide populated overnight.
I'm using over-the-air reception exclusively, as I'm a bit allergic to monthly charges of any kind. Reception with my large rooftop antenna (5 mile line-of-sight to Empire State Building transmitters) is far better than the 4-year-old RCA DTC100 unit I borrowed. This unit had intermittent dropouts on PBS and sometimes other channels. I receive digital feeds for ABC, CBS, NBC, FOX, UPN, WB11, PBS and a bunch of others.
The only slight problem was that I lost all guide info when I modified my channel lineup and tried to get correct info for the PBS Kids (WNETK, 13.2) and Thirteen World (WNETSD3?, 13.3) channels. Still, a day later this recovered and I have complete guide info now, with the exception of the 13.3 channel.
So, I'm very happy with this unit and hope it will keep performing like this.