I've got a question I've always wondered about when contemplating upgrading that I haven't personally seen any discussion about. If I were to upgrade from a 2,1 to 5,1 would I be able to simply swap in the new hard drives? I'm currently running 10.9, 10.11, and Windows 7 Ultimate. For Windows, I figure I would just need to activate again and probably update the bootcamp drivers. However, Mavericks and El Capitan are running with the modified boot.efi files. Wouldn't these create an issue on the new, officially supported, 5,1 hardware? Would I need to do a fresh reinstall, or somehow change the boot.efi files back to the "normal" versions? Just curious on how easy such a transfer would be as my goal would be to keep using the same drives with as little reconfiguration as possible. Any insights are most appreciated!