I have enjoyed this thread. I too have done a lot of recording. Playback at 24/44.1 does sound thicker and richer than 16/44.1 but the difference in audio quality only becomes apparent (to my ears at least) in an A/B. Without the higher bit rate recording serving as a basis for comparison the redbook standard is just fine. I find bigshot's patience at explaining and supporting his views commendable - I find some of the responses he has received unfair. Mastering (and less commonly re-mixing) does without question play a big role in the "new & improved" versions of recordings over and above the claimed technological "improvements".
At the same time I don't doubt the sincerity of those who state they find the new generation of CD to be sonically superior - however, just why this is so clearly remains a moot point.