Photonstophotos now published the real world Dynamic Range measurements of the new Nikon D850. And with the exception of ISO 64 and 400 the 2,5 years older Sony A7rII performed better across the entire ISO range.
Just to be clear, we are talking about minor differences that will certainly not make your photos better and worse. What is interesting about this test is:
1) There has been no DR progress on the D850 compared to the 2,5 year older Sony camera.
2) Sony needs to add a serious native ISO 64 support to squeeze out the best performance (Note: As reported by Jim Kasson the A7rII has a “fake” ISO 64 setting).
3) Sony might has reserved the top edge tech for the 2018 Sony A7rIII model (Note: Nikon surely uses Sony manufactured sensors).
And to not pass as a Sony fanboy. From a usability point of view the D850 beats hands down the Sony. Sony needs to improve a lot and with the A9 they surely did show they are on the right path on this.