This weekend I checked out the other new HD channels on Cox. VH1 HD, MTV HD, and CMT HD: These channels appear to be simulcasts of the SD channels, with mostly SD programming. Perhaps I tuned in at the wrong times, but I never found a single HD program on any of these three channels. Nickelodeon HD also looks like a simulcast of the SD network, with a lot of SD programming on the HD network, though I did find a couple of HD programs on Nick.
Spike HD appears to be a simulcast, but many of the programs and movies were offered in HD at the times I tuned in.
These five HD channels, plus the other 3 recent additions (Planet Green, Hallmark Movies, and Lifetime Movies) earn a "D+" grade for Cox, in my opinion. (8 new channels is a lot, but most of the channels are not very good and/or don't offer much HD programming.)
Looks like Cox went for quantity over quality. Let's hope we don't have to wait another 6 months before we get more HD additions from Cox!