I have a bunch of coworkers who live in the UK. Every few months, they come to Durham for meetings. When they are here, I always go out to dinner with them and bring a different knife each time to show off.
THEY LOVE SEEING MY KNIVES. (I'm also concealed carrying, but i don't tell them about my ccw because I don't want their heads to explode. )
Anyway, last time they came I carried my Microtech Ultratech. It was a big hit. It got passed around the table several times at dinner. They all wanted to pop it out and back in.
Anyway, one of them wanted to know if the spring was powerful enough to shoot the blade through his hand. Luckily, I was able to get it away from the drunk Irishman before he stabbed himself.
Then, I held up a paper napkin and pressed the button. It wasn't even strong enough to go through a napkin. The napkin knocked the blade off the track. It was easy to reset though.
My feeling is. They are really cool. Fun to play with. But mine has failed on a number of occasions, so I do not trust it for daily carry. It's not 100% reliable. (But then again, if I ever do need to defend myself, I'm not going to be reaching for a knife. )