Problem is that pedaling "upwards" with the opposing leg is not more efficient. In fact, it would be less efficient if it actually happened. Contrary to popular belief, cleats and/or clips were not designed to help cyclists pull up. They were designed to keep one's feet in the same spot on the pedals and to keep them from sliding off during competitive cycling events. The most they could do efficiency wise would be to help one partially unload the foot on the upstroke by acting as sort of a constant tactile reminder.

sorry about baiting your response ... not trying to disuade you or anyone else from using them as they apparently work for many riders. It's just a pet peeve of mine when I hear the "pulling up" claims.