I agree Daniel. I did a direct comparison and thought the 70-200 f4 + 1.4 was sharper than the 100-400 at 280. Even cropped to the same image size as the 100-400 at 400mm was better. So, I went with the 70-200 + 1.4. I got the bonus of a great 70-200 lens! I'll know more after the track and field season this spring; the shots on the far side of the track are a better angle from the stands than on the close side. My old 70-300 was adequate but the 70-200 + 1.4 will be much better.