I listen for and like hearing distinct positions of individual instruments sources as well- which I think of as a higher-level illusion built atop the foundation formed out of those more basic recording aspects. Only when those things are more or less correct can I put them out of mind and shift focus to higher level issues like imaging.. and maybe experinece that magic goosebump, spine-tingling 'willing suspension of disbelief' thing. For me, multi-channel playback takes that one step further in listening for the imaging of the room sound itself, the reactions of people from various directions around the room, and even better location of sources on stage when that's appropriate. It's facinating and addictive. You are right on about the quality of the music and performance trumping all of this stuff though. When considering what this is all really about, a cheap mono cassette recording of a sublime performance beats a technical marvel of a recording made of something musically worthless. At it's core, it not about technique and gear comparisons but communicating the information and emotion of the music and the performance.
I've never heard any ambisonic or WFS playback systems myself. I'd love to sometime. But again, I don't think shooting for technical perfection with zillions of speakers would be an appropriate goal so much as acieving a more convincing illusion.
The primary value I find in all of the matrix surround and upmix techniques for music is the ambience extraction to help create a more convincing diffuse ambient field in the listening room which is one of the big components of a live musical experience. In that light, all of them are basically fancy versions of the old Halfler difference technique. In some ways the basic Halfler thing is better in its simplicy and leaving L/R path untouched, as it seems to me that many of the more advanced matrix techniques compromize the direct sound somewhat in trying to get improved differentiation of individual surround source locations which is more imortant for sound effects and movies. When I do mix down my multi-channel recordings to stereo, I usually switch back and forth between monitoring in stereo and checking the DTS Neo6 and Dolby PLII music mode auto-upmixes of my 2-channel stereo mix. I can do things to get the decoders to spread the room ambience and crowd reaction out to the sides and around the room with the decoders on, but I want to make sure that I don't do anything that would compromize the straight 2-channel stereo. Usually I can get things so that it benefits the straight stereo playback as well as the matrix decode, so if someone has things setup correctly and wants turn the decoder on they can, and it's a win all around eitherway.