There was a note at the end of the Manley Mastering Back Bone manual that I found very interesting.
Is theorized that two people may disagree over a piece of high end gear as a result of usage, not necessarily due to the intrinsic sound of the unit.
To elaborate, the section suggests that where a piece of gear lives in the chain, how hard it is fed, and the interplay it has with the piece before and after it affects greatly the performance of a given piece of gear. Therefore, if two engineers , both with golden ears, have completely different impressions of a unit, we have to consider their test configuration. Unless they used the same set up its quite possible that they were listeing to to 'different' units for all intents and purposes.
Of course, the Manley suggested solution for finding your gears' best place is via the Mastering Back Bone, but my gut instinct and past experiences tend to agree that a piece of gear has to be integrated into your chain with significant trial and error.
Best,
GH