I have a D500, my wife has a D750. We are not professional photographers; just enthusiasts. We shoot a variety of subjects. We both really like to shoot birds in flight. We both use the Nikkor 200-500 - 5.6 for that. I have gotten some really amazing shots with the D500 and the 200-500, but the D850 takes my shooting to a new level. The quality of the pictures and the level of detail out of the camera are pretty amazing. The 45 MP BSI sensor is able to really capture so much detail that the difference with the D500 and even the D750 is pretty noticeable. I shoot in RAW 14 bit lossless compressed format, so the file sizes are fairly large, but memory is cheap, and it gets cheaper all of the time, so I would not let that be a deciding factor. The D500´s 10 fps and large buffer are great features, but the D850 can hold its own, especially if go with the battery pack (9fps)(Which I do not have, so I can only go by what I´ve read). The D850 feels solid in your hands, and I don´t think the fact that it is fairly substantial in size is a negative, especially if you have fairly large lens hanging off the front of the camera. The D850 is not inexpensive, but I think that the value is there, and if you decide to purchase one, I do not think you will be disappointed with that decision. I know I am not.