I think that it may depend on the sport you are photographing. I shoot my grandsons playing Lacrosse and use the Fuji 100-400 and feel I need all that reach. With sports like football and lacrosse, soccer, the sport is very fast and moves up and down the field. For these, I usually just plant myself at the 50yd line and shoot a way, using all the 400 mm whenever the play is at a distant corner. The 100-400 is too much sometimes as the players run right in front of you, and with the kids games, the team meets in the middle of the field after the game to shake hands and hand out Player of the game awards. He, I quickly change over to my 18-135 to catch those times, although now, I picked up an X-A3 for the wider lens, so I don't have to change lens out in the open with wind or rain.