Where is it written that Doug's PSK will be replaced if ever used in a survival situation? I think I've read quite a bit about this PSK, but I can't remember to see THAT written anywhere.

Personally, my take on important gear is in fact the oposite: If some gear really plays a crucial role in saving my bacon in a survival scenario, the least I can do is a) let everyone know about it, b) vote with my vallet and buy some more of that stuff.