I have read that sports photographers love the lens (among others). What interested me is that the articles I read (from the Sochi Olympics regarding indoor ice skating, if I recall correctly) was that it is really the camera-lens combination that make the 200-400 so popular. Getting to the whole "tool" argument, the photographers were finding that they could crank the ISO up a stop with the newer bodies and still have clean images which allowed them to keep the shutter speed fast enough to freeze action and they no longer needed the 300 f/2.8 or 400 f/2.8. They could then go with the flexibility of a zoom and f/4 as the best tool available.