I had a CRKT m-16 with the aluminum handles and the single guard/flipper. I carried it for a while, then the liner lock failed. Got to a point where the liner would slip out of place with any pressure on the spine.
Really? My m16-14sf has been used like a fixed blade and the lock is still fine but after a lot of a abuse and big spine whacks and stabbing into wood I did have to tighten the pivot screw because it developed some play.