Thanks to Bedford Photo, in Little Rock AR, I received my replacement 200-500. (the first one had a problem with the rear rubber seal).
I would assume for action/sports this would a great lens, especially with a D7200 or D810 as each camera has excellent high iso. The F5.6 vs F4 on the
200-400, to me is balanced by the mass/weight of the 200-400.
I own the 200-400, VR II, but I guess I am going to attempt to sell mine. It's really too heavy to carry all day in the field, at least for me. I don't see any difference in sharpness between the two lenses, and I get a bit more reach with the 500mm. The bokeh on the 200-400 is beautiful, creamy and smooth, and you don't see this with the 200-500, at least I don't. But it's a matter of which lens I am going to pick up to carry.
The 200-500 is also no light weight, but still is lighter/smaller than the 200-400. Optically, I just don't see any real differences.
Paul C