Midi, I respect what you have to say but don't understand your reasoning. You can get a used universal player for as little as $50.00, then a disc is a disc is a disc. Given the sorry state with brick walled CD's the higher rez formats are usually well worth it, much more than a "slight" improvement IMHO.
I have not seen such a "universal player", or it was not touted as such. Exactly what players do this? What do they play and what do they not play? And what about playing the disc in the car.
I don't share you enthusiasm for Dolby Surround, an abomination in my opinion. They bastardised quad to make a surround system for movies. The link between surround and movies rather than for music has never yet been broken. What you describe as QS/DS would better be described as RM, true RM can properly place images around the room without regard for specific "channels" and can be referred to as a kernel system rather than a matrix one. I understand your fondness for it. While I would agree about the connection between QS and DS our friend OD would insist that DS is related to SQ instead. Both SQ and DS do share the same Lf, Cf, Rf and surround encoding after all.
I really favor RM. I play back in DPL2 because it fixes the side-image location problem.
I have some classical music in DS.
All of the following are RM: D-diam, DQ, EV4, Scheiber, QX, QS, DS, DPL, DPL2.
All of them are effectively the same system. The only differences are the speaker locations, the front and back separations, and the delays in DS playback that fix the side location problem. The recordings of any of them can be played back on all of the others. These recordings are not centered on specific channels. The 4-corners encoders may specify certain channels, but you don't need a 4-corners encoder to encode sounds to any position.
I encoded a sound effects recording for a stage play in the D-diam system in 1970. I placed sounds in practically all positions in the circle around the listener. So it can be done with any of the RM systems listed above. It is discrete that needs specific channels.
No, DS is not really related to SQ. It has the same encodings the D-diam system has. The only SQ coincidence is the speaker locations and the encodings for those exact locations. But the locations of other sounds in SQ are encoded in totally different ways. And ALL of the RM formats listed also share nearly the same Lf, Cf, Rf and S encodings (other than the holes the basic 4-corner encoders leave in CB).
Don't look at the encoding equations. Note that if the only difference in the encoding is the phase of the signal with relation to other signals, it still decodes the same way. Look at the Poincare sphere loci of the encoding points, not the encoded phases.
There is no difference between the encodings for DS. Only the decoders differ for DS, DPL, and DPL2.
With the RM encoder I use, sounds can be placed in any position in a circle around the listener. And (other than the side location problem) all of these systems will place the sound in the same place. DQ and EV4 will place the images slightly differently from the others, but moving the speakers puts the images where they would be with the others.
As for not wanting to purchase mail-order, if I had such an attitude I would only have maybe a half dozen surround releases in my collection. It's even getting hard to find regular CD's locally and those that are for sale are not the ones that I want for my collection.
I do mail order from well known companies. But they don't sell these special formats discussed here. In fact, I don't encounter them anywhere other than eBay.