Yup, but Soundhound and I did a test one afternoon quite a while ago in his personal studio, calibrated for professional application. (He mixed commercial films there.)

We both could clearly hear a difference, even with careful level matching. The Dolby compression was audibly more lossy than the DTS, less smooth, with less clarity of detail (manifest primarily in a loss of acoustical ambiance in the music tracks.)

And do I have the temerity to place our informal testing over the testing of the magazines, movie studios and music labels?

Damn right, I do. :p

In the last analysis, it's nothing to lose sleep over. But a difference is there and it sounds related directly to the compression algorithms.

The difference that you SHOULD lose sleep over is the difference between the original audio stems of the soundtrack and the chewed-up, compressed versions of BOTH DD and DTS. The amount of sound that those compression schemes throw away is heart-breaking.