Upload & Sell: Off
I betcha a nickel to a doughnut that of all 100-400 users' shots, at least 99% are taken at 400mm FL. Do you think that 200-400L will be any different ? So much for zoom "versatility".
Besides, Markle, 200-400L will probably be too heavy for you to use handheld.
I can only address my shooting style which I will describe as spray and pray. I will often let go with a burst of 10, 20, or even 30 shots with my 1d4, often times at 400mm.
On the other hand I do a lot of chimping and frequently will zoom out for better framing.
The result is that most of my shots may be at 400mm, but I would bet a fair number of my keepers are at a focal length other than 400mm.
Back in the day the Photo 101 prof use to say expect to get 1 keeper out of a roll of 36 frames. With the decrease in cost using digital I expect 1 keeper out of 100 images I capture.