I decided to go with the LCD-4z, and just received mine!
I have auditioned LCD-X, LCD-XC, LCD-2, LCD-3, LCD-4z, LCD-MX4, Arya, D8000, Empyrean, Ether 2, Ether Flow, ADX5000, HD800 S, Focal Clear, HE-1, HD650.
It's been quite a ride, with a repeating pattern:
1) getting interested in a headphone
2) reading rave reviews, getting more excited
3) then reading one or two negative reviews, having everything thrown into doubt again
4) getting interested in a more expensive model
and repeat
I don't doubt that the 4z isn't perfect, and that other headphones outperform these in some ways. From my experience, quality really did scale with expense, and there's a lot of headroom for that in this hobby. Happily, the 4z brought me to tears when listening to some of my favorite songs, out of the box, with no break-in - I had never head this music like this before, it feels like hearing it for the first time. They blow my Adam S2X midfield monitors out of the way.
I love it when a new piece of tech has that effect on me, even after having been around the block a few times, and becoming more difficult to impress each time.