I was born on the South and am damned proud of that fact. Equally proud am I of my ancestors some of which fought for the South during the War.
For the last couple of years, I have watched monuments dedicated to Lee, Jackson, Stewart, and other generals fall at the hands of a ruthless mob or at the hands of cowardly administrations in city halls and on college campuses. After the monuments to the generals came down, next came the statues to the common soldiers.
At the time, America was warned that if you allowed these statues to be destroyed, the next thing you would know, these anarchist would come after the statues of Washington and Jefferson.
The retort was, "Oh that will never happen!" Well guess what? ... not only did these idiots destroy the statues to Washington, but also down came statues of Grant, Lincoln, the 54th Mass. Colored Troops and a number of abolitionist.
It is obvious that the people who have called for desecration of these monuments could not tell you who fought durning the War Between the States much less the motives of the participants. The true motive behind their actions was not the debasement of Confederate monument but the desecration of everything America.
Within the last two weeks, after the profanation of the Jefferson monuments, I have notice a major change in the narrative of the news media's (this includes Fox) description of the Confederacy. Before, the new outlets would say the statues of Confederate soldiers were bad and needed to be removed because the South fought for slavery (not a 100% correct analysis) but now the new claim is that they need to be removed because the Confederates were traitors.
The spineless news outlets have changed their tune because they now cannot defend Washington and Jefferson because they too owned slaves. They cannot condemn the Confederates and not do the same for these founding fathers. They had to do a "one-up" by now calling them traitors.
You can bet that the day Robert E. Lee declined the offer of Gen. Winfield Scott the position of commanding General of all US forces, the farthest thought on Lee's mind was that of a traitor.
Shame on all you houses CNN, (BS)NBC and Fox.

I do have all three. Kept the D810 when I got the D850 in order to have two full frame bodies. Still like it for the smooth, quiet shutter but am slowly coming to prefer the D850.

I do like to do night sky photography, using regular lenses for the visible night sky. Some day, I might be interested in expanding to telescopy, in which case the broad spectrum D810a would be very interesting to me, but the glass in ordinary lenses blocks most of the ultraviolet light that the expanded range sensor is designed to capture, so it won't work for me right now. Having the infrared sensitivity would be a problem for what I do, because it can already be a challenge to get rid of "horizon glow," which mostly come from infrared. The big problem for me is that the D810a is not usable for normal visible light photography, so it ends up being a pretty big expenditure for limited use.

I have not used my D500 for night sky. It was my last camera purchased, and I was already established with full frame equipment for that purpose. I do have a friend at my local camera club that uses his D500 along with the Nikkor 10-20mm zoom for that, and he gets beautiful results. That's why I sometimes question those here who claim that the D500 is poor at high ISOs and has unacceptable noise. It certainly seems not to be a problem to him. And if you look at the Photons to Pixels curves, there is very little difference between the D500 and the D850...maybe half a stop or so.

I have found the primary benefit of an accessory intervalometer to be the ability to do free form input of exposure times greater than 1 second, while the in-camera ones use the camera's native shutter times...1, 2, 4, 8, 15, and 30 seconds. This is not enough flexibility for night sky photography, where I regularly use 20 or 25 seconds (and yes, it does make a difference).

I use Nikon's MC-36 intervalometer on my D810 with great results. I have not used it with my D500, but it didn't seen to work quite correctly with my D850.