With Zeros, if you're an "inward heel" guy or gal, you can reverse the cleats. I think you can also grind the retention piece to allow "improper direction" clipping out, but not having actually done it, you're on your own, and if you do, good luck with the warranty.

SPDs are really nice for allowing either-way clipping out, and you really don't have to buy the special-option cleats for bi-directional release.