It appears Starz is doing much more (or starting to) HD. I think tracking native res for upconverts will not yield any additional info as it will show 1080i from Starz, the upconversion (if happening) coming prior to sending.
Chicago has some very dark and filtered light effects. I can just say a more funky lighting mood cinematography movie like Black Hawk Down looked fantastic on Starz, so the source material and how it comes from the studios makes a big difference.
Some is criticism is subjective, I have seen the Chicago DVD being on worst lists and best lists for transfer, but there has to be a "bit shortage" for all the moving so HD (even an upconvert) should benefit from the bandwidth.
Take an SD film on HBOE (4:3) and the same SD film on HBOEHD. There is a world of difference, even though it does not approach true HD.