Yesterday I listened to LPs of Aja and Gaucho back to back. I wouldn't say Gaucho was that much brighter than Aja. Maybe the horn sections were a little bright on Gaucho, but that LP was one that received better treatment.
More generally, I would rely more on well-recorded classical orchestral pieces and jazz for auditioning components. They can inform about both timbral accuracy and soundstaging better than pop/rock records, which are generally multimic'ed with artificial reverberation and often EQ added. When auditioning gear, I did use a few rock records because I was very familiar with them and wanted to be sure they would sound good, since I listened to rock as much as classical and jazz.