My similar older model Shimano SPD mountain shoes are my most comfortable ones, too. I've had them forever and love using them on my commuting fixed gear bike exactly for that purpose (walking around easily, and being extra comfy, easiest to get in and out of). In the city fixed and on the mountain bike, SPD cleats with comfy shoes are perfect. Their efficiency falls off though when spinning much higher gears, and least for me. They don't allow nearly the same efficiency of power transfer when spinning a really high gear as stiffer LOOK and SPD-SL road specific shoes, nor their stability when really pushing it. I would never use normal SPD pedals on a "real" track bike or a road bike for an extended period of time. But, I know people who do and are fine with it, so to each their own.