That's pretty close to what I do.
I have HDHomeRun with a dual tuner feeding EyeTV on a MacMini, which exports to iTunes which feeds two ATV2's. The export mechanism is automatic and seamless, including metadata. Works very well!
So far, I don't watch live TV unless I'm in front of one of the computers (which all have EyeTV installed). I watch everything recorded via Apple TV.
But I'm going to pick up a Channel Master ATSC receiver to feed my projector and TV. Mostly for when company comes :-)
I forgot - it's a current MacMini - 2011. I also used my 2010 iMac before I got the Mini. The export mechanism is resource-intensive, and the iMac became all but unusable during exports.