In the fall of 2006 I took the clipless pedals off my commuter so I could ride in winter boots. By the middle of the spring 2007 realized I hardly missed them. I time my rides occasionally, and my best time home is usually about 25 minutes. This was true before and after switching back to platforms.
So I laugh at all the talk about how much more efficient clipless pedals are. If you're a hardcore rider they probably offer a small advantage and certainly in extreme conditions like a very steep uphill or a mad finishing sprint they are worthwhile.
The truth is that for most commuters they are not worth the bother of switching shoes, clacking on the floor, unclipping at lights, etc. Ride with them if you like them, but don't fool yourself that they offer any advantages.
Donning asbestos suit.