On my regular bike, I've got clipless pedals. On my folding bike I didn't, but going down hill, I had to stop pedaling as my feet kept flying off the pedals. I felt horrible not being attached to the pedals, so I put dual sided pedals on and everything is much better. I find it much safer.

I bought Nashbar's commuting shoe and find that on even surfaces, I don't get the crunch.