For me the real question here is the Mercury recording approach. It seems to me to have been regarded as a sine qua non in high fidelity for the time, but also lauded simultaneously as somewhat minimalist in comparison to some alternative technologies, such as Decca/London Phase4, which was regarded as stressing hi fi thrills over a natural perspective. I know that in Detroit at least Mercury placed great emphasis on the Hall, initially Orchestra Hall, which was being supplanted at the time by the acoustically monstrous Ford Auditorium, and also experimenting with Cass Tech High School. Get the Hall right and good things will happen.
I bought a few of the Paray recordings when they were released in SACD, namely theCharbier collection and Berlioz Symphony Fantastique. Wilma Cozart Fine was supposedly not involved in these digitalizations and viewed them as tragedies. To my ears they are spectacular, enhancing the originals to no small degree