I was taking an avy 1 course up at Mt Rose in Tahoe last week. I NEVER ski my FT12 Dynafit inbounds... I tend to get my 200+lb body moving a little faster than I like in the dynafits just cause well it's often groomed and wide open (STH16 cranked feel safer!). In any case... I was going to make a hi-speed slashing turn up a little convexed roller and managed to pull the Dynafit toe piece out of the ski at 40mph or so. The binding was still on my boot and the ski was skidding to a stop with the heal break dragging.
So! I now feel way safer in the binding. I would never ski like that in the backcountry and don't feel like I am going to step out easily.
My thought on why the binder pulled out? The FT12 has a very narrow screw placement, even though there are 5 screws. My ski has 100+ wide center area where the binding was mounted. The G's from a turn like that need to have a way wider screw placement in any ski.
Anyhow... for me it was a revelation in the bomberness of the Dynafit. It was hard to transition to it for the first few days out... "How do those little pins on the side of my toe hold me in?" Now I know... If you ski BC a lot, Dynafit or bust!