Timtruro, Yes, exaggerated performance gains even if you're using them as intended vs. platform pedals. SPDs with treaded mountain bike shoes will allow you to walk around near normally, great for charity/social rides.

If you use toe clips the performance advantage is nill, but there is no toe discomfort or strap loosening prior to a stop. Foot action when disengaging is different. Insted of a lift and rearward movement simply rotate the heel outwards.

Brad