I just know the battles WNED had trying to get 1080i and two 480i subchannels... it's why they switched to 720p for a while. Although they're back to 1080i now; I think they may have upgraded their MPEG2 encoder.

MPEG4 really is the future - much more efficient than MPEG2. But for it to happen they're going to have to mandate that new ATSC decoders can handle it (for at least 5 years I'd guess) before we'll ever see a blip of MPEG4 transmission.

All I know is the quality on NBCUS isn't that great. It looks better than "crummy internet feed", but I'd say not as good as WNED's subchannels.