I had a bit of free time here at work, so I shelled into my mythtv box, did a few minutes recording, then ftp'ed the mpg file to work so I could check out the quality. Result: looks like flawless HD programming in the two minutes I watched. (Sorry for the small sample size, that's all of ET Canada I could tolerate...).
Forgot to mention earlier, this is a VHF-Lo Yagi, attic-mounted. I can't remember the brand (not CM) but it has about a 7' boom. It's pointed directly toward Camp Fortune. The interwebs tell me I'm about 35km from the tower.