I just read a post and someone said they didn't like back locks as much as others. Sal posted asking what it was that they didn't like. I think this question came from him to better understand the opinions of his customers.
We all have knives that "just fit" in our hand better and may not be able to explain exactly why. It seems to me we can get more specific about why we like or dislike a particular lock. Once in a while someone appears asking questions about choosing a knife because they want one nice pocket knife after years of cheap ones. That was me about 35 knives ago. Since the lock is such a significant part of a knife opinions on them may help that guy.
I say "Why do you like liner locks?" You say "I like them, they just fit." I'm hoping for something more detailed as to why you like or don't like a lock.
Using the lock: I prefer liner locks because they seem to take less movement of my hand or repositioning of the knife to release the lock. A back lock, ball bearing lock and others I've used seem to require more hand activity to get the knife positioned to release the lock.
Lock reliability: Any lock that won't allow the moving parts to move as a result of putting pressure on the blade spine I feel is reliable. Putting pressure on the spine of a slip joint will close the blade because the way the blade is held open is a gradual point of contact. The point of contact of locking knives should be at a 90° angle so one piece won't move against a spring because you pushed on the spine. Actually, the spring shouldn't make the lock stronger, just force a part to move into the locking position. There is a lock on a competitor's knife that has an excellent design however the spring in the knife broke on me almost 10 times between two or three knives with the same lock. They need a better quality spring to make this a great lock. One inferior piece in the lock design made the lock unreliable.
Lock strength: How much force will it take to close a locking folder without releasing the lock? With Spyderco knives I think this question is mute because every single knife locking design will pass this test. If normal use, even a little abuse will force a knife to close then there is something wrong with the design or the lock is broken or dirty. So, I guess the question here is how much force will it take to break the lock?
I think every Spyderco knife's lock design is more than adequate in the strength and reliability categories. That being said the ease of releasing a lock will make more difference in how we like a particular lock over another IMO. Try this with knives with knives with different locks that you consider strong and reliable. Whittle on a stick a little, then pay attention to what it takes to release the lock. Does it feel like a natural movement? Does the lock release easily? How much danger is there in cutting yourself when closing the knife? Plus any other thoughts.
Hopefully your thought will be more brief than this post.