I shoot prep school soccer and lacrosse, mostly in late afternoon and evening games. I used the Nikon 300 f2.8VR on the FX format D3 & D4 and on the DX format D2Xs (on which it is functionally ~450mm), and was very satisfied with the results. But, I sold that lens because I really prefer the flexibility of the 200-400 f/4 for those fast moving sports. I usually keep a 80-200 f/2.8 on my backup camera, but the 200-400 was the right lens for just about every shot. Both the D3 and D4 have excellent low light sensitivity, so the loss of one stop on the f/4 compared to the f/2.8 is not really missed. The sharpness of the 200-400 approximates that of the legendary 300 f/2.8 and also provides excellent foreground pop and bokah. Although more expensive than the 300 f/2.8, the 200-400 f/4 is much less costly than a 400 f/2.8. I recommend taking the 200-40 out for a game or two. Even if you don't like the zoom, an examination of the data on your photos will tell you if you shot more at the 300mm or more at the 400mm setting, which should help you decide between the 300mm and 400mm prime.