I've finally had a chance to try out a 200-500 and now I have to make a decision: Will I be happier with this lens than my 150-600mm Tamron?
Disadvantages: Higher cost. (Not crazy, though.) Doesn't go to 600mm and I do admit I like having a lot of zoom range to work with. When you photograph space launches from a distance, you need all the zoom you can get!
Advantages: Even when NOT in sports mode, autofocus is fast, at least as fast as the Tamron. It doesn't get lost in autofocus as easily as the Tamron.
Sharpness: I don't know if can tell the difference.
Given my overall financial picture, I wouldn't be able to keep the Tamron if I bought the Nikon glass. It's one or the other.
Give me reasons to push me in the direction of the 200-500.