If you get a 722k with the optional OTA Tuner Cartridge you can record 2 Satellite channels, and 2 OTA Channels at the same time. You can use all 4 tuners at anytime; this means you can record 2 Satellite channels, and one OTA channel, and watch one LIVE OTA channel at the same time, or Record 2 OTA channels and one Satellite channel, and watch one live Satellite channel at the sametime.
I love my 722k, I'd have a very hard time giving it up. Having the ability to use 4 separate tuners all the time is awesome.