I suppose I should be a bit more detailed about my ZT Hinderer. It had a sticky lock from the very first, but the application of the sharpie several times did wonders for that and I noticed that as long as I wasn't sloppy with disengaging the lock it wouldn't start sticking again. Lockup was a little over a half and there was no rock or side-to-side movement. The detente was rather weak, in the sense that to flip it open I really had to use good technique and also had to strengthen my index finger. I got pretty good at this but sort of envied the people who could ignore that because they had strong detentes and could build up a fair tension before release. I originally also used the thumb stud, but because the stud is placed in an awkward position it's not an especially ergonomic way of opening so I finally decided that the flipper was the way to go, and that the detente on mine was too weak. Also, I wanted to use the knife in the tip up position on the left and found that the mounting screws for the clip wouldn't grab on the G10 side, so wrote to see if ZT would send me longer screws. They said to return the knife. Since I was returning a Skyline anyway (off center) I could just put it in the same box for the same price. So they're both at KAI getting "the treatment."
The 561 is actually a little big for me, since I have smallish hands, but it still felt pretty comfortable because of the well made ergo handle. The 3D machining on both the G10 and Ti-Lock side is beautiful. I'm not sure that the bearing system works as well as the one used on the Spyderco knives, but it's pretty nice and worry-free, although I haven't tried it in sandy/dusty country. I have the 566 on pre-order.