Thad, I've been on this for the past few months and it's taken me some time as well to understand digital media.
You are right about the source material etc however all things being equal, high res files offers Dynamic Range.
A lot of lesser recordings by run of the mill studios are "hot" - in short they are louder and hence grab your attention. This is at the cost of dynamic range and loss of detail. Transients, low level detail, etc are sacrificed. The Linn recordings are some of the best I have heard. However, the material you get at other places are debatable. You also have to look at your DAC and how it processes the signal. My DAC has the S/PDIF inputs limited to 24/96 whereas input via USB goes upto 24/192. Big difference in sound quality when I use the USB input.
If you get some of the things not quite right - you will not hear the difference. In that case it would be better to stick with the resolution at which you get the best VFM. No point springing for the extra cash if you can't hear the difference.