Bandit,
The one occasion where I had that problem was shortly after I got a new pair of skis. They were completely set up by the ski shop (the tech is experienced, and I trust him). Skis are Volkl S4, and the bindings are Marker LT 11. I don't remember exactly what happened, but for some reason I ended up with a lot of pressure straight forward, and severely bruised my shin bone. First of all I though I had broken it.
I am not disputing what you are saying - you, obviously, have a lot more experience than I. But, theoretically, should they release on forward pressure alone? I would think the DIN would have to be set really high to prevent accidental release under high pressure turns?? I have never had a problem releasing under other circumstances. Maybe a walk out every now and then.