A german YouTube said that the nano texture glass makes the image softer than it dos on the XDR. So apparently this is lower quality (at half the price).
He also states the iMacPros internal speakers sound better. But i am using bose external or headphones anyway.
He is editing 6k50fps footage in real time via the internal SSD and claims that this would be very choppy via USB-Ceternal SSD. So adding some TB of internal space might actually be a futur-roving advantage unless you use 10gb ethernet to edit.
He dos some real world testing with 6k were the 2020 iMac renders fast than his iMac Pro. While his 2019 iMac (fusion drive mind, but specked out) takes about double.
Under Windows the 2020 iMac also outperforms the pro in 3DMark (Scores are: 6500 Pro, 7500 specked out 2020)
Playing games in UHD is no problem. No comment on fan noise though.
Conclusion, if you got a very old Mac, get it. If you got a recent Mac don't get it.
He barely mentioned ARM, wich i love him for because every other YouTube seems obligated to spend 1/3+ of their video on it.
For exact specs on his machines check the video, he has them written out on screen during the bechmark.
The gaming looks smooth as butter. UHD? Impressive.
Azrael.