Page 66 of the latest/Fall-Winter '05 Rivendell catalog has an interesting essay by Grant Petersen that argues having your foot attached to the pedal offers no real benefit. His sense is that there is a small increase in efficiency (to help get through the difficult spot between 10:30 AND 1:30 in the stroke) and being clipped helps keep your foot on the pedal when hitting potholes or when the pedals get wet and slippery. But --> then he notes how much easier it is when unclipped to get on/get off, how one doesn't have to worry about which shoe you're wearing and, what I found most intriguing, how you can use more muscles unclipped than when you're clipped in (because you can vary the position of your foot).

I've been riding with toe-clips or SPD's for decades now, so going unclipped just feels weird, and I don't think I can be objective. What do others think about Grant's points?