lot of Canon sport shooters went to Nikon when Canons keepers went down with the AF problems in the 1dmk3, the D3 was much better as a sport camera and Nikon followed up with D3s , compared to 1Dmk4. At the Olympic Games in Beijing there where many Canon shooters moving directly to Nikon because of the low keepers they got with 1Dmk3.
The lens line 14-24 , 24-70, 70-200 and 200-400 Nikon lens was also a big argument to move over to Nikon at this time. Nikon have increased the number of users from a few up to 50/50 in some events, Canon is still Nr1.
Funny, I CAN speak from experience. I shot the Big Ten track meet this year, and out of all of the sports photogs there, there was ONE Nikon shooter. Everyone else had a 1D Mark IV or 1Dx and ALL of them had a 400 f/2.8 for their primary lens.
And I CAN speak from experience of watching from the sidelines
. Here in India there was the Indian Premier Cricket League (quite a big national level event here) and out of the 23 photogs, 19 were using the great whites (yes, I counted them from the stands and the count is correct unless anyone was using lenscoat skins for the great whites).
Now the way I understand, the great whites cannot be mounted on the D3 or the D3s ... so I leave you to guess which cameras the pros were using.
1DX, 5D3, 600D, RX100
16-35L, 24-70L II, 70-200L II, 100-400L II, 50L, 85L II, 135L, 17TSE, 24TSE, 40, 100 macro, 18-55 II, 55-250 II, 1.4x III, 2x III, 600RT x 4
When it comes to gear, it is better to vote with your wallet. Bitching on online forums like a lunatic doesn't get you anywhere!