I'd love this ability as well... I currently have a WiRNS/ReplayTV setup which can only take SD channels (and I also filter out the channels I really don't care about, bringing my total channel count to 66, reducing wear on the modem, and minimizing the amount of time I spend baby-sitting the guide data download process each week), and things are set up perfectly for it. However, I'm in the process of adding a MythTV / 3-tuner HDHomeRun Prime box into the mix -- gotta deal with Comcast moving to all-digital, thus effectively obsoleting the BeyondTV with three analog tuner cards which my husband has appropriated for himself. DH requires that he has access to at least the same set of channels as what he has with BeyondTV (about 100)... and if I add HD (ESPN, ESPN2, Golf, etc) to the mix, he may even forgive the 10 extra clicks it takes to do anything in MythTV. And yes, I can turn all of the channels back on in my default lineup, but Replay download time will triple... be much nicer if I could have two lineups from the same source.