Cox has this in the Tulsa market as well... These Plus channels are above 860Mhz and only received by the Trio boxes. I don't know how Cox gets by with advertising no HD fee for the channels you subscribe. My ultimate package has all the Plus channels but they stick the HD versions in the Plus and charge extra for it. I tried the Trio boxes (POS).
What I don't know, is if any of the cablecard tuners (Ceton, SiliconDust, Hauppauge) can tune above 860Mhz? If so, I don't see how Cox could restrict your access if you package included.