Yeah my problem (with clipless - or even cleats of any sort) is that a lot of the times when I've stopped, there's still a moving line of traffic beside me. And a lot of my calm mental state on bikes is due to the knowledge that I can in a second flee the bike and be hoofing it to the sidewalk :)

Owow on the seatpost snapping though: I've recently become paranoid that at some point when I'm off-saddle, the axle the pedals are on will go.