Just exactly how much of these discussions is fueled by machismo and fantasy, IMO pretty much all of it. What is a real life survival situation, and if your in one why do you need a big knife, or any knife for that matter. I think there are a lot of things on my list far above any knife.
If you are lost, chances are one maybe two nights is about all you will spend in the out of doors. What do you need a knife for, where I live I don't need one to build a fire, if I am lost long enough to need to build traps I am in very serious trouble, thinking about self defense is almost stupid, again if it comes down to my pocket knife against a determined foe, man or beast, I am in dire straights. If you are injured to the point that you can't walk out, then I would rather have a whistle than a knife.
Mental masturbation?:jerkit:

My wife likes that analogy...
I keep a standard list, some more expansive than others, but they all have a listing of "essential" items for me. We just spent all day yesterday hiking and bouldering around at Enchanted State park here in TX. The only knife I used was my Spyderco Military to cut some sandwiches in half...did I "need" my SAK Outdrider, Fehrman Last Chance or Fallknive WM-1? Nope. Knives are a hobby, but they are also just standard items I throw in the truck, pack or EDC as a habit.
I also CCW and have never used it, but when I'm out and can legally carry, I always pack it...they are numerous items I use more often or would most likely be more productive outdoors or in an emergency situation, but it's a part of my "essentials" list that I've just worked to make a habit of carrying them.
I try not to establish a priority list, as each item is critical in their own right and some are more important than others depending on specific situations.
I use 550 cord, 100mph tape, LED Flashlight, First Aid kit and a good water bottle/bladder with water filter much more often than I do a whistle, signal mirror, compass or emergency shelter; that doesn't mean I would forego packing them, they are an integral part of my "essentials" as is a good, quality fixed blade knife and CCW.
Granted, this is a knife forum after all, but with proper planning (including your EDC), there's no need to have the "you're in a survival situation with just X, Y or Z" scenario.
If I'm planning a backpacking trip I do balance weight with items I consider essential for redundancy. Knives, cordage, fire-making and signaling (I also consider water essential, but it encompasses a good carrier and filter/purification methods, and yes on a planned trip I do have redundancy in those areas as well).
Ignoring the all-in-one compromises, you can't use a knife for a whistle and you can't use a whistle for a knife; you may not use or need either for the majority of your backpacking/hiking trips, but when you need either, you need to have them on you.
ROCK6