It never would have occurred to me that there was any particular skill involved in riding on flats as I have done it all my life so it just seems natural. But so many people are posting that they have no confidence in their ability to stay on the things and that they hurt themselves when they use them that I'm now reconsidering that. Apparently, it's difficult for some people not to bang their shins with their pedals. Who knew?

Interesting you mention stoplights because (and I know this will sound like boasting, but it's true) in an urban setting, I am consistently faster starting on a stoplight than just about any non-motored vehicle I encounter-Stomping onto a big flat pedal gives me a big jolt of power that I don't think I could get if I had to clip in. Again, I don't really know that as I'll never ride clipless. But it really wouldn't at all surprise me if a habitual clipless rider wasn't as good starting on a flat pedal simply because they haven't got a start-up routine suited to the pedal style.

My suspicion has been that there's almost no difference, and my dad always said that the most heated arguments are generally about things that don't matter. When things matter, most times the "right" answer is obvious.

One thing I've noticed about these arguments is that it's going to be impossible to settle them by any kind of study because no one can agree on who the test riders should be. If all pro-level cyclists train a particular way, it only makes sense that they'll be better at that than they are the way they don't train, so it's really not likely you're going to get a group of elite road riders who are as adept at riding on platforms as they are clipless. And if you use average amateur riders, people will say that the lack of difference is because they're not good enough riders to realize the advantages of clipless (or spinning, or whatever).

The second thing I've noticed is that the safety arguments on both sides sound like unmitigated BS to me. Nothing is perfect, but they're both safe.