Nice review!
Upon testing the AR5000, I found the positioning on the measurement rig plays a very significant role in the FR you get. This is expected. As Amir mentioned at the beginning of the review, the AR5000's drivers are highly angled. That means a greater degree of variability in how they interact with the pinnae.
Wear them with your ears towards the front of the AR5000 ear cups (blue curve) tends to give you the most upper-mids and treble, compared to wearing them in the middle/back of the ear cup (purple/red).
p.s. I am using the GRAS 43AG-4 namely the regular IEC60318-4 coupler so the treble response can be a bit different from Amir's measurement.