I can't stand the ball-locks, but they ARE more secure. I can open the tri-act 'beeners with my right hand, which only has the last three finger left. So I consider them a necessity, since I absolutely cannot open those teeny little ball locks without using my left hand. In the winter time, you can pretty much forget about opening the ball-locks with thick gloves on.
I actually had my triact Petzl-William open up on me once. It was all bound up in a bunch of rope criss-crossing it, and it got just the right combination of pull-rotate-and slide. I should have cleared it from the crossing ropes before that ever happened. No problem, but it was a bit scary. It could have turned out badly.