Ill at least agree that the 400 really is the lens to go for.
I wouldnt bother with the 300 especially since you already have the Sigma. The 400 does everything the 300 does only better. The only place it falls short (IMO) is basketball (though I have used the 400 for basketball a couple times) and volleyball. For everything else (Baseball, Football, Soccer, Lacrosse, Field Hockey, Track, Swimming, Tennis..Really every other sport I shoot) the 400 is definitely the way to go.
I was actually thinking of selling the Sigma (just don't love it). I was afraid the 400 would limit me and since I'd be almost exclusively outdoors with it, I figured I could just give up a stop of light and throw the 1.4 on the 300 (and save a crapload of money in the process).




