This really has been a fantastic thread so far.
I have to point out that the rescue knives mentioned that cost the lives of a helicopter full of marines weren't just called rescue knives by the manufacturer, they were also called rescue knives by the Navy's purchasing department. Someone behind a desk probably saw a deal and thought he could be a hero by making numbers look good. I've heard other examples of equipment, materials, and other supplies brought in via military purchase departments that really didnt' cut the mustard, and seen a few myself. I don't blame the manufacturer for that... I blame the guy who decided the knives were good enough to be issued for the task. He made the judgment, and he paid out our tax dollars on a knife that would be used to come to the aid of one of our soldiers. Had the decision been left to the men doing the job, I have no doubt they'd walk into a knife shop and look around, and make an educated decision based on their own experiences. With all due respect Mr Emerson, it's not your words, your arguments, your viewpoints, or your warranty that have made your knives a success. They're all fine and good, and in your world (and mine) they count for a lot. But it's the results that count.
If I had to pick the best knife for personal defense in the city, I'd go with a big folding knife... why? Because (and I'm paraphrasing Bob Terzuola here) the most important quality in a knife used for personal defense, (I would say tactical, but semantics seem to have bogged down the issue) is that you HAVE IT WITH YOU. And in most day to day cases, that means a one handed folder. It's just not practical for me to walk around boston with a Ka-Bar or a gurkha attached to my belt. The chosen folder would probably be an emerson. I'm generally not too worried, becuase usually there's a wine bottle, baseball bat, pool cue, wrecking bar, or something else really big with a good reach on hand. I don't claim to be a skilled martial artist, so whatever hits hardest and ends the fight the fastest will do for me. They all make lousy prybars, (with the exception of the wrecking bar) so I suppose that makes me an outcast.
If I was a soldier, who needed a dual purpose tool, I'd find me a big sheath knife like an old, cheap imported gurkha, which is only heat treated on the edge, so there's no chance of the whole thing snapping. If I wanted something nicer that held a finer edge for much longer, a strider, Busse, Emerson, or...? And a good, lightweight sharpening stone. Something with no moving parts to worry about, no screws, etc. There's no possibility of lock failure if there's no lock. And I'd bet dollars to donuts a piece of 3/16" blade steel stock with a point and a decent edge probably doesn't even have one of whatever it is that would break on most folders, and would cut someone out just fine, for less money, and with more reliability. And if a Naval purchasing officer supplied my troops with an untested knife that snapped in half, I'd put him on the next helicopter to that ship, to let him explain to them men why they lost their buddy.
Would I generally use a big folding knife as a prybar from day to day? No, probably not. I don't like nails and screws f***ing up my edge, and since, as a civilian, I live close to things like a hardware store, I have the luxury of being able to buy a $5, 8 inch prybar that fits in my pocket, and can be carried around in my truck, and then use my knife as a knife. If you're really that finicky, get a foot of 3/16" stock, turn one end into a knife, and heat treat that end, having the other end formed into a prybar. But there's really no real need in any paved society to use a $200 folder like an $5 tool, even though you could. Can you use a folding knife like that? Sure. Is there something better?
I'll quote CRKT. From what I've read, they made an outstanding knife that did well in this test, and as the manufacturers of a knife that held its own, I'll count their word as much as I would Ernie's. "A knife is the most expensive and least effective prybar you'll ever own."
A soldier who carries everything on his back has an excuse to want one thing to do it all. It saves on space and weight. I, on the other hand, have a truck.