Back up options for Canon 1DX

I sold my 1D4 last year and have just the one big DSLR body, the 1DX. I am going on a trip soon that will involve action shots of wild animals. Clearly the Sony A7R would not fit the bill. I am looking for alternatives to purchasing another 1DX which would be too expensive.

I am planning to have a 70-200 f4 on the 1DX and the 24-70 f2.8 on the other body, with two BR straps so I can use either camera as needed. Fast autofocus and high speed (minimum 4 fps) would be required. The animals would be close enough that a long lens is not needed and everything would be shot handheld from a standing or sitting position without tripods.

I think the 6D and the 5D3 both are in the running. Just want to hear some opinions from the experts here. I don't need landscape options since I already have the Sony so my need is purely speed and focus on a full frame. I am planning to buy used, and both the 6D and 5D3 are within my budget. 

I would also like to keep the second body for a while, so the possibility of product replacement with newer models is an issue, but since there is nothing on the horizon as yet, it probably does not matter so much.

Thanks in advance,

Pradeep

I'd get a 6D, much cheaper than a 5D3, similar pixel count to your 1Dx, same frame size and the best low light performance of any Canon camera.

was just thinking about a this too as I need a backup for Africa for me and a primary for the wife.

E.J. Peiker wrote:I'd get a 6D, much cheaper than a 5D3, similar pixel count to your 1Dx, same frame size and the best low light performance of any Canon camera.

Thank you EJ. That's what I was thinking. The only reason to go for the 5D3 would have been the similarity of the setup and controls (I think in a rush situation it helps of both cameras have identical button and control layouts), but the cost is almost twice as much.

Will go for the 6D.

Pradeep