Interesting. Maybe sibilants issue is depending on the tracks you listen. I have a list of “sibilant prone” tracks in my library. HD800S had sibilants on 90% of them. ADX5000 had only 10%. I guess these 10% are just how they are recorded.I agree with all points, except for the sibilance bit. My experience is the opposite. I am completely fine with the treble on the HD800S, but I had to use the Loki Mini to tame the treble of the ADX5000.
But I agree that despite a smaller soundstage, the overall SQ is nicer.
Another note is that even when there is sibilance, I can tolerate it on ADX5000, while it was unbearable with HD800S. Maybe fuller mid is helping this or amount of sibilance is lower with ADX5000. Anyway I’m happy. Of course, YMMV.