But in all honesty, the only time I've ever come out of a clipless setup while riding fixed (of which I've used both Shimano SPD's and Look Keo's extensively), it's almost certainly because I fishtailed the rear end and didn't keep the foot exercising the upward force in line with the frame. And it's only exacerbated by worn cleats.

In spite of their easy engagement, the lack of adjustable tension is a huge downside to Eggbeaters. I've heard mostly good things about Time ATACs, but have never had the time or money to justify trying them out. In fact, trying out any clipless setup is an expensive proposition.