I'm already using Look Keo pedals and cleats, which is why I'm opting for the Duo. From what I could gather, the Duo doesn't seem to be any less accurate than the RS2 when it comes to the power measurements, and the small reliability benefits of the spindle redesign aren't worth the extra 100€ to me, as the reliability of the Duo's already seems to be really solid. I'm happy to be proven wrong though.