While not a contrary opinion, I'll give some other factor to consider.
• What sport makes a difference, some benefit from high FPS and for others, 4 FPS is sufficient. • Some sports are hard to frame — you need to back off a bit, enlarging the field in frame, to better guarantee capturing the action. • Downsizing the D800 file to the 12 megs of the D3s yields a D800 image with nearly identical image IQ to the D3s. • For your other, non-action subjects, the D800 is da bomb!
You may be interest in threads by a sports photog and his experience with a D800: