Depends on what I am shooting. Lets look at two examples.
example 1. Nikon 500mm 5.6 lens, subject bird flying at 75 feet with the D850. You get the shot but have to crop. Result, about 15-18 mp on the bird.
example 2. Nikon 500 mm 5.6 lens, subject bird flying at 75 feet with the D500. With this lens you do not need to crop because you have an effective focal length of 750 mm. Result, 20.9 mp on the bird.
WINNER, D500.

Example 3, Nikon 500 mm f5.6 lens, subject bird flying about 30 feet with the D850, result is, you don't need to crop, result 45.7 mp on the bird.
Example 4, Nikon 500 mm f5.6 lens, subject bird flying about 30 feet with the D500, result, at an effective focal length of 750 mm, you only get part of the bird because you are really too close with this lens and camera combo, and even if you fit the bird in, you only have 20.9 mg on the bird.
WINNER, D850.

Just tying to show you what each camera is capable of, each has it's strength's. So, I shoot with both bodies with the 500 f5.6 lens. And I use each on wildlife and use either bodies depending on the environment.
PS. I have the D5 battery in the D850 so I get 9 fps vs. 10 with the D500. So, no biggie.

Interesting post. I own the D850 and at 9 fps using the XQD card I can easily get up to 51 consecutive 14-bit lossless compressed raw files in a single burst. That's enough for 5 seconds of shooting, something I rarely do.
I usually shoot in Jepg and can shoot all day without filling the buffer on the D850.
I also own and shoot extensively the D500, similar results.
I have been shooting both for wildlife and neither one has run out of buffer room yet.

Yes, the D500 shoots at 10 fps. The D850, with special battery, shots at a much slower 9 fps.

NO, but, get this, it includes a special case.

This lens is a SPECIALIZED lens that 99.99999999999% of us, including professional photographers will never need.
To quote Nikon:
"Shooting point light sources like stars and nighttime cityscapes at wide apertures usually requires post-production correction for sagittal comma—an aberration where points of light appear distorted, like birds spreading their wings. Noct intensively eliminates sagittal comma across the entire frame, so point light sources are captured as perfect points of light, even at the peripheries."
"When subjects are backlit, incidental light can streak across the frame causing unwanted ghosting, reflections and flaring. To counteract these anomalies and ensure crisp, clean images, Noct employs two of Nikon’s most advanced lens coatings: Nano Crystal Coat for eliminating incidental light from a diagonal direction and new ARNEO Coat for eliminating incidental light from a vertical direction."
"Noct adopts a large-diameter ground aspherical lens element crafted from the finest glass, with outstanding surface accuracy. It has a high refractive index unattainable with molded-glass."
And lastly, it is a MANUAL focusing lens.

Yes, use the lens hood, you do not want stray light from the stadium lights entering your lens, and, it adds additional protection for your lens.
A like to use F6.3 on that lens, gives great results. So, at F6.3, when you get there aim camera at player about in the middle of the field and adjust your ISO until your shooting at 1000 sec. or higher. You could, at that point, use those settings and just go manual, the light will not change but at a HS stadium the light may fall off at each end zone, but you can also check these when you get there.
I don't know if the D800 has GROUP AUTO FOCUS, but if it does, use that focusing system. Continuous Auto focus is also suggested and the highest fps you can get.
Good luck and keep on shooting until the end.

Are you happy with the results you are getting? If yes, keep it, if no, get something else.

Provided you are using the same lens on both camera's you get more EFFECTIVE MEGIPIXELS on the subject with the D500 using the same long lens to photograph a distant object.

This is now your second post about a lens no one can afford. Want to make it three?

Many things can be done in PP.
If you can't use PP then you need a much longer lens. When I had similar faces I used a longer lens, like a 135 to 200 mm. The wider the lens the more distortion you get, especially if you 3/4 filling the frame with the face.

I have shot professional portraits for over 35 years. My favorite mm range for portraits was 100-200. So your 70-300 would do. Shoot wide open as you want the back ground to go out of focus. Distance your subject from the back ground also, do not have them up against it. Focus on the eyes.
One of the most miss understood beliefs in photography is that a 50 mm lens captures what the human eye sees. This is so WRONG. All of my photographer instructors have said the lens that comes closest to what the human sees WITH BOTH EYES OPEN is a 35 mm lens.
IMHO, my favorite portrait lens was the 70-200 mm 2.8 lens. Loved that lens for portraiture.

Interesting again, I put this on yesterday and Administration moved it to another area. But you say even less about the Z50 than I did and Administration put your post on the photography forum. Interesting the way they treat two individuals with the same subject.

I believe Nikon refurbished lenses come with a 30 day warranty?

Yes, it is definitely the photographer that matters, every single click of the shutter.
And your analogy is wrong in comparing an axe to a chain saw and making it sound like it's the same with camera's. It is not the same. Bad analogy.