I've used Shimano SPD 520(540?) for a few years and liked them a lot;
commuting, club rides, 100 mile charity rides, etc.:
https://www.youtube.com/watch?v=FFyX...IoDLA&index=53
Got dragged to the weight weenie side and switched to single sided 170 gm. Xpedo R-Force(the cleats are SPD compatible):
https://www.youtube.com/watch?v=Fh5V...6zPoymgKaIoDLA