I agree that balance is a good thing. For a while I had a rather large wallet on one side and large chiropractic bills to go with it. When I got into preparedness I started carying a flat rolled hank of nylon cord on the other side. Balanced things out nicely but I discoverd that having that sutff back there still caused me a pelvic tilt that was very bad for me. Now All that is back there is empty pockets. I make up for the lost pocket space by wearing a Filson vest with enough cargo capacity that I can camp without a pack. It's all about the choices.

Certainly you could carry quite a bit of information in this manner. Another possibility is carrying it on microfiche. There was a thread on this that included some small colapsing loups for reading later. Search for microfiche in the last 3 or 4 months on the forum search.

I think that you will rapidly run into capacity problems trying to substitute reading material for training. A wise selection of traveling companions and EDC gear will take you further than any instructions that you might have with you when you are in the muck of the situation. I think that the flat roll of 200' of nylon cord that I carried would be more useful to me in a situation than an euivalent weight of reading material. The problem is that if I know how to use the stuff and I have enough of the right stuff then I don't need the reading material, OTOH, if I have some of the stuff but need to sit down and drain the battery on my Photon II in order to learn how to use it then I will have bled out before I get off the dime. Emergency situations are not always urgent but they often are. In an urgent situation the last thing I want to be doing is reading to find a solution of waiting for someone else to read about the solution. In a non-urgent situation I am more likely to want the dice game or the micro-sized deck of cards or the miniature bible or selected verses to keep my spirits up while I huddle in my debris hut warming my face to the fire just outside the door.

Only time that I see this sort of thing being useful is during training or during the situations where there isn't any urgent need but the duration could be effected largely by our actions. Example - lost without knowledge of proper signalling or orienteering. In this situation one could wait in vain without signalling or walk deeper in without proper orienteering skills. It is certainly possible to learn to use a mirror from a small wallet sized card but if the individual purchased the cards and carried them in place of the mirror then what? They read the card for the first time and discover that they should have bought that mirror before taking the trip - I hate it when I do that!