G50AE, I have to disagree with you on some points. A six-inch blade on a knife may or may not be legal in some areas so that's something that must be considered. A bigger blade doesn't necessarily make it more deadly, it's the operator that makes it deadly.
It's not like stopping power. If you have a 6 inch blade but only contact with the last 1 inch of the blade, it's the same as getting all of a one inch blade. If you get cut with a 6 inch blade to the back of the arm, it's not the same as getting stabbed in the throat with a 1 inch blade.
In reference to "stopping power", who's worse off: A person getting shot at with a .454Casull and missing or a person getting shot with a 9mm center mass? If the operator is skilled, he/she can make any blade efficient for slashing/stabbing. Furthermore, carrying a knife with the intent to use it for defense or bragging that the knife is for that purpose may not agree with your local LE.
No, Spyderco and most all other brands and professional makers don't have videos of their knives' abuse. I guess they all must not be very good because they don't have a video. I agree that lock strength is important in a folding knife. I've done all sorts of stuff with my Spyderco and never had the lock fail.
If in the event one is concerned about said lock strength, one can remedy that by going to a liner lock or new locks like the Axis lock. Personally, I think that if one is to do work that is so heavy that the lock strength may be in question, I think a fixed blade knife is in order. Folding knives and most knives in general aren't prybars, screwdrivers, or swords and they shouldn't be treated as such.
You may be interested to know that Spyderco uses AUS-8A steel for their blades. Some of the newer ones use ATS-55, while a few use ATS-34. You can get into a lot of debate as to which is the better steel. AUS-8A is similar to 440C. Compared to ATS-34, it's usually a bit less in the edge-holding but better in the corrosion resistance department; but not by much.
Serrated knives don't necessarily have to be sharpened by a pro. If one doesn't feel confident about it, that's the way to go, but there are good sharpeners out there like the Lansky and Spyderco that work perfectly with serrated edges. You can also use a round stick ceramic stone on each of the serrations, depending on the type of serrations, though it's time consuming.
There are a ton of junky knives and a ton of good knives out there; there are however, no universally "best" ones. Only the ones that are best for you. Regards.