I've got the A520's on a couple of bikes, the M324 (campus pedals) on another one. The 520's are lighter, but not well suited at all for riding with regular shoes. The M324's are your basic platform pedals with a SPD Cleat on one side. As such, they work very well clipless and unclipped. I've never had serious problems flipping the right side over when clipping in, and at the very least you can pedal on the flat side until you get going, then get clipped in. Down side, they (the 324's) sure aren't stylish, but they do just what I need them to do. That makes them a good tool for the job.

One thing, if you have more than one bike, be careful about some of the variations (SPD Compatable) pedal / cleat combinations, ie Nashbar, Wellgo, VP. They may LOOK like a shimano SPD, but a lot of the time the cleats aren't compatable due to small differences in design. This may or not be an issue for you.

Hope this helps, both are good functional pedals, but the 324's sound like the ones for you.

Steve W