^ I never saw being one-sided as a disadvantage. The A-520s are 315 grams a pair, which is almost as light as you can get with SPDs. If weight is a big concern, Crank Brothers makes less massive four-sided pedals, and Speedplay can get you down to about 200 g, for ~2.5x the price. But the A-520s have been very, very comfortable and work well for me.

Here's a list of pedals by weight, although I think it's a bit old:

http://weightweenies.starbike.com/li...hp?type=pedals