I've felt bad about not being able to give the AM21 a workout so far because I didn't have access to my rooftop antenna and relied instead on an amplified set of rabbit ears that got me a whopping two channels. But today I installed a SWM-8 which in turn freed one of my lines into the house so I could hook up the antenna again. (It's an amplified antenna (Antennas Direct "Lacrosse") which means I can't diplex it.) Now I get bunches and bunches of channels, and almost all of them come in perfectly on the AM21, better than the HR10 (I never tried the HR20.) I was especially happy to see all of the digital channels from the two Boston PBS stations (2 and 44), though apparently the signal from the NH PBS station is too weak based on the directionality of the antenna.