I definitly noticed the Fox East/Global HD signals last week on the Simpsons. The opening of the Simpsons started early on Fox East, so I saw the Fox HD feed, which had noise on some of those background lines/flicker in them, then the Global HD feed kicked in after and I saw the opening again, none of the issues that were easily noticable on the Fox feed. I didn't even try this week, watched Global HD and the quality did look really good.
I find the quality on TSNHD to be good, but there are those little compression/macroblocking on any type of movement, and the noise on the scorebar is really annoying, and before I hear maybe it's the tv, the same football game replayed on TSN2HD looks way better, no noise and better picture. Maybe it's the fact of having a Pioneer 60" Kuro that is showing all the detail of the image, including the bad detail. The NFL games on Sunday afternoon looked bad on all channles. I remember the day of 1080i CBS NFL games, truly amazing quality, not anymore.