As some have assumed, the OP said nothing about an eReader being the sole source of information.
I would suggest that the best solution is to have both a paper survival manual AND an eReader. It is not feasible to carry multiple books in your BOB, but you can carry a whole library in an eReader. If the battery dies and you are unable to charge it, you still have your paper manual.
Welcome Treeseeker! Nice first post. You caught a lot of us with our "all or nothing" thinking caps on. Carrying both seems like the the best compromise to me.