Opted for the Click'R pedals (£23) and tested them on the Upper Thames 200 yesterday. Set them to near max tension, given this approximates to the low end (which I use) of m520s; using 51 single release cleats. No problems at all, and found them even easier to clip into - probably because the binding is 'popped up' at an angle relative to the reflector platform. They are a tad heavier than the m520s but not an issue for me...