I didn't change the colour balance which for both cameras were "Auto W/b". Not sure why there was a slight reddish cast for the Zf, unless it picked up reflections of indoors lights in the window?
The D1X is left panel and Zf is right panel, so your assumption is correct,
As to the similary in details, which at first seemed a bit unexpected: both cameras have in fact an identical pixel pitch on the major axis approx. 168 pix/mm. The difference is for the minor axis where D1X is only 44% of the Zf in terms of pixel pitch, thus clearly inferior as far as maximum resolution is concerned. However, for nature scenes, this might not be as limiting as one would think since Nature rarely displays a fine-gridded pattern.
The red cast is probably refleksions.
I had a D2X and sold it quite cheap for about 500 Euros many years ago. The new owner was very happy and he wrote back that he liked the way it rendered. He was a professional photographer.
For me the D5200 was a big step-up in quality. Both resolution and ISO performance. Maybe he could see some in D2X images I did not notice. It was a very well made camera.
Now I have a Z50 and for me a step-up compared to D5200. Even that Z50 is only 20 MP. I look at Z5 in the moment as there are some good offers. But I wonder how much of a difference the images will show.
The IBIS is nice for non VR lenses and also the better ISO performance and also that the DOF is less for portraits etc. Maybe when Z6III arrives the Z5 price will drop further. I am happy to be a little "behind" and then save a lot of money. But if Z6III comes out as a 40 MP of so wtih better ISO performance than Z5 I may be tempted for a Z6III or if Z6II drops a lot. Z50 is almost vintage now?