I believe these are wonderful performances but the sonics are demonstration quality. It’s like Mahler composed and orchestrated these symphonies with audiophiles in mind. They allow the all the sonic attributes of our systems to shine.
I’m not familiar with Chailly and the Concertgebouw’s recordings of the Mahler symphonies, but I agree with you about your comment on the pieces’ audiophile potential. I have several that are wonderfully fun to listen to, including a DG SACD of the 2nd performed by Kaplan and the Vienna.
I find that an effective test of systems is not small group or solo recordings but large, complex works that really challenge the system.