This isn't technically an answer you're looking for, but I had the same problem and went clipless. I was using Power Grips, but would keep catching the lugs on my shoes as I tried to "unclip". I liked the Power Grips, but couldn't deal with not being able to get out of them quickly.

So, I figured that if I was going to be wearing special shoes (with a flat sole), I might as well just wear shoes that were cycling-specific and were less of a hassle to cycle in.