Damn, all of this high ISO talk and tracking talk just makes me want to go on safari with the 1Dx MkII but I know that if I make this purchase my better half will severely injure me. Maybe I should upgrade my medical plan as well as place an order for this thing.
Is your 5D3 gripped? If so, then you might be able to make the jump to 1DX (and sell the 5D3 + grip) without her knowing anything (other than the missing funds in the bank account). 






