My first set of clipless were the Shimano A530's; flat one side, SPD on the other. Bought them thinking they'd be versatile as I could use them in flip flops or normal shoes. I rode them for nearly a year, and only once or twice ever wanted to go out with normal shoes. The hassle of sometimes having to look down and flip the pedals at lights and stop signs was more of an issue, so I bought the double-sided M540 pedals recently; no regrets