I love skydemon, it's a great navigational aid in the cockpit. My tablet is 8.4" and is (to me) an ideal size: not too big for a small cockpit, and big enough so you can read the map.
Still, I always carry backups: my 5" phone (also with skydemon), some built in gps device, printed charts and plog from skydemon, and an old (2 years) DFS chart. That's 4 backups.... should be enough
