I have commuted with Look and SPD pedals. I bring a pair of regular shoes with me and change into them. Once, I got caught out without my bike shoes and had to ride home with regular shoes on the SPD's. It was OK; I took it easy and made it.

I find that I can get into the Look pedals faster from a stoplight than my SPD's. I used to ride a lot of MTB; back then I was used to the SPD's and I was fast in them. But now, the tread on the bottom of the shoe messes me up.

My vast preference is SPD, because I can walk comfortably in the shoes. I always walk around a bit getting the bike ready to go, locking up, and going to my office. My SPD shoes have ski-type buckles, so they're quick to get on and off, too!