True, but with any kind of showing, an HD2 could be a valuable part of their "added value" game. Agencies always demand "added value" these days.
The understanding of HD subchannels is so limited that agencies would not, in their vast majority, be convinced. They want bonus spots, events, digital, etc.
In that way, agencies are smart. While spots on an HD channel may be "added" to the buy, there is no "value".
One station with ground clutter ratings produced by a couple of PPM meters does not make a real audience.