I'd be great if someone here with a 7.1 system (Not using Atmos heights) could also suss out (Abbey Road) any major differences between the "surround" speakers and the "rear surround" speakers; to see if it's worthwhile to combine those two (digital edit), for us with just a 5.1 setup
So far my observations of an unscientific A/B of Abbey Road (songs Come Together, Here Comes The Sun, Golden Slumbers, Carry That Weight, The End).
Sonically overall, I think the dts takes the win. Crisp, clear, "warm" sounding not as bright as the True HD but don't get me wrong, the True HD is bright but not painfully bright, just the dts is warmer, less bright, and I prefer that (could also be because I'm listening with horn loaded speakers, so something that's bright to begin with, sounds more high pitched on horns IMO). My experience with Dolby is that it is typically bright on any recording, music or movies. Overall though, you won't be disappointed with the dts 5.1 as all 5.1 speakers are very active. There is definitely an overall recording difference between the dts and the True HD. The True HD is no doubt recorded louder by a solid 3 - 5db.
5.1 dts
It's as if you are sitting dead center just in the front of the band as they play. The rears/sides light up with guitars and chorus in each song as if they were singling and playing next to you. Good depth and imaging with the dts but depth (and soundstage) is where the True HD wins.
7.1 Dolby True HD
This has the added dimension of the back speakers. So now you are completely surrounded by the Beatles as they play through the songs. The True HD downmixed Atmos makes it almost as if the singing and instruments have a lot of depth and are floating around in the room. Very "airy." (I can't begin to imagine how awesome this would sound with 4 more height or ceiling speakers.)