I just registered the other evening and this is my very first reply.
The survival saw mentioned IMO is a very weak argument as a survival tool. The photo given in the above link as an analogy, would be similar to scrubbing your floor with a toothbrush. If you had all day and the effort you might get through that 6" limb and maybe you won't. Chances are 1" limbs are all you need, however a folding limb saw can be carried in a back pocket and can make a pile of firewood before you ever make it through one branch. Forget the wire saw. If you feel the need to saw, pack dental floss. At least your teeth will survive.