I have mostly flippers now, except for a couple of Blurs and a Speedform II. I really like the flipper when it works, which means that the detente on a manual flipper has to be strong enough to allow some tension to build up before it's released. I'm probably going to pack two of my current flippers up and send them back to KAI to have the detente strengthened. I can deploy them but it's like I have to meditate on it or something, and it's just tiresome.
BTW, I tested the detente thing by bending the integral lock bar inward increasing the detente temporarily. It made flipping very easy and reliable, in marked distinction to what I'd been experiencing before. The only problem is that that doesn't last longer than about 20 or 30 openings. The detente needs to be re-tuned.
Update: After some checking, I doubt that ZT "tunes" the detente, although I don't know that for a fact. I know that Hinderer won't tune the detentes for the XM just to make flipping reliable, so you take what you get. Good argument for only buying a knife in person, I guess... or, just buying assisted openers (or knives with that option just in case). I should also say that opening the ZT with the thumb stud is extremely reliable, so that's probably what I'll do. Nice that there's *that* option.