I have been with DirecTV since 1996 and am very happy with their constant improvements. I have a HD DVR in the family room (1080i TV) and a HD receiver in the bedroom (1080P TV). Has anyone noticed that around the holidays the clarity of the picture is equivalent to 1080P and not just the movies? Then after the holidays it seems to go back to its normal strength transmission.
DTV used to (they probably still do) dynamically change and compress the picture quality and resolution. "Premium" channels like HBO/SHO usually got priority and the rest went downhill. And they'd dynamically change it depending upon bandwidth. The move to MPEG4 (I think) was supposed to relieve the bandwidth constraints, but I understand they still adjust things as they see fit.