Let me add my 2 cents and hopefully get back to the original question.

First two points:
1. SERE and the choice of equipment has little to do with a day pack. VERY different problem, different solutions. Even the course equipment is different from what experienced people carry in the field. The course usually sets limits on equipment and you are required to spend a certain number of days in the field. It ends when the course is over. In real life you want to get out FAST! Even in the 60's many carried 2 survival radios and extra batteries - in place of food and even ammo. Extra mirrors (they were glass), smoke and flares were important.

2. Long term survival has NO real part in the discussion of a day pack. You should have left a trip plan, notified people where you were going, carried a PLB - in short this is a limited time problem. Food is comforting, not necessary. Being warm, dry and found is the critical part.

The equipment in a day pack can be divided (for survival purposes) into three areas: The items you carry for the reason you are in the woods, The items you carry for use that day that can be helpful during a survival situation and The true survival equipment that you carry ONLY for survival use.

The first group is normally just slightly useful for survival, ie Cameras, hunting equipment, tools (I am a geologist and carry a rock hammer, etc). They can add considerable weight but we willingly carry it because we want to or have to. Not my impression of the topic of this discussion.

The second group is important, but once again we carry much of this for daily use and would carry it anyway (although weight here is certainly of more importance). As an example, our primary water bottle is not carried for survival. It is however very useful. In my case I carry a small stove (MSR Pocket Rocket) because I like tea and often soup for lunch and in many places it is bad manners or very time consuming to build a fire like I did in the Rockies in my youth. Although these items should be regularly surveyed to keep the weight down, their primary use may dictate a different standard for them.

The third group is the equipment you carry for survival. Here there are many outside influences on what you carry and the weight to value considerations. When I am working in Florida in the summer, a sleeping bag is not in my ruck. It goes in right after signaling if I am working in Alaska. How far I may be from help is also a big question. If I work in Northern Alaska, carried in by helicopter, I plan for a longer stay than if I am enjoying the leaves in the NC mountains.

In all of this, my prime criteria is that I can stay comfortable (where I am) until help arrives. My first priority is getting help (a PLB, signal mirror, flares, whistle, aviation radio (part of the second catagory), etc.

If you would like to see what I carry for a specific situation, let me know.

Respectfully,

Jerry