I think honestly, it depends on how you're going to commute and what the road situation is like. For a 5 mi commute from the train station to the office, I was on my road bike and wore my clipless. Honestly, I like riding fast. Not only because riding fast rules, but because in Orange County, CA... it helps for when you have to hop out of the bike lane into a left turn lane, or when there's no bike lane, or something like that. When you're around cars, it helps to keep up with the flow of traffic best you can and I found being clipped in gave me the speed to do that. It'll take you some time to get used to flicking out of the pedals at a red light or stop sign, but eating it at >1mph at a stop sign in front of a blonde in a convertible is just something every cyclist has to go through.

I have a pair of cleat covers that I snap on when I'm off the bike, walking to/from the train, car, or office, or any other time I have to walk. These are like $15 and worth every penny. I carry my shoe shoes in my backpack, along with my change of clothes for the office.

That being said, if you're taking a shorter commute, or are in an area where you can leisurely ride without declaring Mortal Kombat against cagers, by all means, use platform or MTB pedals... if you find them comfortable.

This hyper judgemental pretentious bike shop in your town, should probably have some sort of loaner program. I know a lot of LBS that do and a lot that don't, so maybe inquire with the Judgey McJudgeersons that run that shop. See if you can ride a week with one and a week with the other. They might not, since they think everyone needs to be built like Chris Froome, but the chances are good. They do this with saddles a lot, and it stands to reason they'd have some tester pedals there.