I let the people of the Internet pull in the shows from OTA, or what ever source, edit out the commercials, encode them into H.264, and pack them into MKV files. I just fill up my HDs with the shows (and eventually buy them on BD when available).
I find most every show I want to see, but I've not looked for anything from those three example channels you gave.
I use
www.Thepiratebay.orgor
www.torrentday.comand usually find everything I am looking for. I tend to like torrent day better.
I find the quality is just as good as the original HD broadcast without the commercials.
I actually don't have a need for a PVR.