"I keep hearing there is a difference in compression (can't remember if DD supposedly has more or less than DTS), but I have no idea what difference in sound that compression difference would make. "

I was told that DD is 12:1 compression, while DTS is only 3:1. I basically amounts to DD using more lossy encoding. Similar to ripping MP3s at different bitrates. The higher the bitreate the better it sounds. The numbers above may not be accurate. It's just what I heard from a buddy of mine.

Pete