Being the trekking pole editor, I've used many, many types of poles. I'm also really, really hard on poles- I've broken something like 7 of them and I've sure made some slip. I tend to jump off small cliffs, particularly when snowshoeing or while reviewing poles. But truthfully, I've found most of the newer twist lock poles to be very reliable. Sometimes with a very hard landing, I'll get some slippage, but it's no big deal. I've had flick locks and their Komperdell counterparts slip too with a really tough landing.
I think the deal with slipping twist lock poles is that you're going to get more slippage if dirt or dust enters the mechanism. I rarely adjust poles once they are to the right length, except for travelling. And when I get some slippage, I'll take then apart and rough the surfaces up with sandpaper (or sand or rocks in the field), rinse them off, and reinsert. No more issues.
There are some that have had bad luck with twist locks but I haven't and most of our reviewers at BPL haven't either. Might be bad luck or it might be some other factors such as grime, lack of maintenence, or undertightening (I tend to overtighten). I'm not really sure.
But you can't deny the simplicity and reliability of the flick lock systems- they're great. But they're heavy too- especially the Black Diamond models. At the end of the day, though, I'll go for a 2 section pole over a 3 section (50% less mechanisms to fail) and a fixed pole over the rest. Fixed poles tend to absorb shock better becuase of more uniform flex and they eliminate nearly all maintenence issues.
That said, I've been using a Komperdell C3 for many, many trail miles now and these poles have yet to slip. That includes scree fields, scambles, the whole bit. My first gen Alpkits never slipped either- and that includes a Rainier climb with a long, rocky approach. Still, I know what you're saying about trust. That's why my fixies are usually in my hands.