The Z1R are... special. They're an acquired taste. A bit like Wasabi or the cyclops on Rolex watches. Loved by many, hated by as many. You have to appreciate it the right way.
I knew Sony offerings well (from the old days, Qualia, R10, CD3000, etc) and ordered the Z1R before listening based just on design information and developer interviews. The impact on arrival was mixed. Presentation was absolute top notch and jumped to #1 immediately (meaning physical presentation here - case, the industrial design with no extras besides the necessary, the overall feeling of quality that later won top industrial design awards). It contrasted greatly with other offerings I had that cost almost the same (Like the 800S, which was a lot flimsier, looked a bit like something out of a Happy Meal next to the Z1R and it just isn't all that comfy even for a guy who loves Alcantara).
But in terms of sound, it was not an immediate full mind-blowing experience. It was a lot darker than the CD3000, less airy and spacious than the HD800, with a bit less sharp separation than something like the Andromeda.
But at the same time, with such a silky, buttery pleasant signature, and sounding so good at low volumes. And very spacious for closed headphones. Separation and positioning is excellent for a closed model. Comfort also shot straight to #1, and they remain the comfiest headphones I've ever used in the hobby. They sound very airy for closed cans, feel built like a tank and have the finishing of a luxury fully hand-made product - which they are... and have a fun, punchy full meaty sound that makes music enjoyable, truly fun even when not technically accurate on the FR chart. They're the fun roaring v8-engine car that makes you smile silly while pushing the pedal and volume, even if your Tesla S is a lot faster and a lot more "accurate/efficient" on every spec on the chart.
Yet, they can sound too dark sometimes, slightly veiled and with a boomy sub-bass. Depends on the mastering of the track, and often it's easy to compensate that in the source (iFi's 3D ASP does wonders, for example). But still, that means it's not a 10/10 like I had hope when I ordered it. A modern MDR-R10. It isn't so. But the R10 wouldn't be as good today, since out standards are more demanding. We're commenting out of memory and respect for the old classics.
To me, the Z1R is one of my favorite closed model. I can see why some people dislike it, as it's not a tool you can use for every task. They're a spoon that excels with soup. If Sony discontinues it fast (as it often does) I would not be surprised if it becomes a valued model in the second hand market, as it happened with models like the CD3000 (bashed initially and later sold at 3x what they cost 10 years before).
Comfort-wise, however, there's no doubt for me regarding the Z1R being king. I think I will still eat my mouse mat if the 820 surpasses that... that and the physical design/assembly/materials/box/overall build quality.
But, when it comes to sound, I'm also a big HD800 fan and still want a Z1R+HD800 hybrid. That would be my apex in sound, comfort, build and.... value/price. Can Sennheiser pull that off with the 820? Nope. I don't think they will be able to this early. But who knows, I'm going to try to find a pair and figure out if the dynamic duo needs to become a trio.
TL;DR: I want a Z1R+HD800 hybrid. Fave closed with fave open. Give it to me, 820!