My apologies for a late reply! To be honest, I don't do much action / wildlife photography anymore, so I really have no use for such cameras. I primary shoot with Nikon Z mirrorless today - I sold off pretty much all of my Nikon F lenses and cameras.
As for the D4s vs D5, I guess it depends on your priorities. The D5 has a better AF system (due to faster processor and low-light AF detection range), so if you need something for fast action, it is certainly the camera to get. The D4s can be bought at a bargain price, so if AF is not your priority, I would choose that camera instead.
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