Yeah, I've done many, many blind tests. For me, the best way to describe DD vs THD (or anyother SD track vs lossy) is openness. How everything becomes tighter, yet transparent. Vocal track becomes more intelligible, foley effects can sound more realistic, bass becomes tighter rather than boomy, panning effects as well as the holosonic soundfield become more apparent.
Here's what totally surprised me. I had a girl I was dating come over to watch a film. She wanted Enchanted, I wanted Die Hard 4. I won. I had the unrated SD in the player let her watch the assault on the apple computer actor's apartment. Then popped in the B-Ray with DTS-MA and did the same sequence again. I thought her 1st reaction would be "it's louder!" but instead her reaction was " I can hear the wood splintering!". This is coming from a woman who thinks THX is a rare STD.
One only has to educate someone to understand what to look/listen for and you can change them forever.
I totally agree with the marketing comment though. Of course they want to sell more discs. Kind of like 1080p on a 37" vs 720p at a 8 foot viewing distance. Complete BS. Now, that's another thread altogether