Two brand new direct from ZT, three used, and one brand new from a reputable dealer. I don't remember the serials. The two direct from ZT were both limited editions. I had one blade crack on a used, like new LE which ZT fixed by sending another knife which was pretty bad and there are pics of it in the GBU folder from earlier this year. They sent yet another one to make up for that and that was a damned nice knife, but not for my use.
One was used, like new, production model which I still carry sometimes. Another new from a dealer is good which my wife carries.
I sent in two separate knives out of the six. Sold two. Kept two. None of the LEs I kept for whatever reason came up with them. Two failed due to straight up bad manufacturing defects, terrible locks, terrible grinds, or cracked blades or a combination thereof. One wasn't terrible and I sold it off with disclaimers for a steep discount. One was extremely nice but not for duty use. One is adequate but not to be trusted in rough use because only maybe 1/6 of an inch if the lock bar touches the lock face, which I still own. And one is pretty good with no complaints, but my wife carries it and doesn't do any kind of hard work with it.