I use an F2AS/MD2-MB1 as my "insurance policy" whenever I am shooting on back-country excursions, when batteries have a curious tendency to fail. As well, I rotate in and out throughout the year an F2A and a pair of F2s (DE1s, all with drives) in order to keep all in working order. No techno-phobe, I also use an F6 and a trio of F5s...