When the movie is available in widescreen HD, I will watch that on channel 395. But if it's pillar boxed on HD, then I watch it on the SD 169 channel so I get it as full screen.
I've done this for years with no problems.
But recently I've noticed that the SD 169 channel picture quality is dropped and is looking almost fuzzy/soft. This is really noticable when there is a "movie intro" and you swap between the HD 720p and SD 480. Before there was a difference, but th SD still looked OK, and better than it does now.
I'm not sure if this is related to the move from MPEG 2 to MPEG 4 a while back, or if bandwidth was reduced on the TCM SD 169 channel.