So far, I haven't seen a compelling reason to go for an AT9. With the triple that I am putting up this weekend and my OTA antenna, I should be set for some time.
NGC-HD would be a nice improvement. In their chart from their plans, they showed a few new HD channels being added this year, hope that is one of them. Another one that would be nice when it goes to HD, would be The Travel Channel. But haven't seen anything on that one yet.