Now that Nikon has put the D850 on sale, I think I will finally pull the trigger on one. The memory card slot options on the D850 are new to me. I have always had my cameras (D610, D750) set with the card in the second slot as a backup to the primary card. For all you D850 users, my question is: what memory card(s) do you recommend for this setup (CFE, XQD, something else)? Also, I have several Sandisk Extreme Pro SDXC Type 1 cards in hand, used in my D750. Are these functional in the D850? Many thanks in advance for your collective expert advice.