I did a A grade level Soccer shoot last night, the Z9 on a 300 2.8 VR II, and a D850 70-200 FL, overall it was excellent, i yet have to go through all the images, the D850 at 9fps had 300 images, the Z9 had 27 GIG of images mostly because it was the main camera., the D850 did the close in goal area and performed brilliantly, the D850 was set on 25 points NO TRACKING.
12800 iso on both cameras shooting F2.8 was very good and not an issue under outdoor LED lighting, single point DR also delivered.
The Z9 was used with 3D tracking and it was hit and miss a lot but i need to work on that somewhat.
The D6 from my colleague by comparison was defiantly just stickier.
I enjoyed the Z9 dynamic range colour, focus acquisition speed, while the D850 didn't have the FPS of the Z9 its image quality was just as good.
The take away's
The sweet spot focal range would have been better with a 100-400 in F2.8 meaning i could use just one camera.
Focus attack speed of the Z9 was excellent
12800 iso was completely fine for both cameras.
FPS on the Z9 was excellent.
Overall detail and image quality of both cameras was superb.
The tracking and lock on of the Z9 is something i really need to work on harder..............