It all depends on the versions you buy.. Funny I see almost all but a couple Nikon guys leave the football field when it is raining. A Pro Canon and L series lens is sealed, so the sand story wouldn't hold up. I use mine from wildlife to studio.
The Nikon D800 is Amazing quality in Studio.
The Canon 5D MkIII almost the same quality in Studio
the Canon 1Dx is so fucking fast and the ISO settings are stupid with low noise.
I can shoot on the new football fields After Dark at 7,000 - 10K ISO wil low noise. Easily taken care of in Light Room.
Now with all that. My 5D Mk3 does suffer from the "soft" photos syndrome in outside or mixed light settings
Can't wait for a recall and get that fixed like they did the 1Dx