My son's bike has Chorus Monoplaner calipers. I am impressed by them. I rate them between the ubiquitous Campagnolo Record single pivot caliper and their later dual pivots. I appreciate the lighter force required with the dual pivots. I have set up one otherwise Classic Super Record equipped bike with dual pivots, there is an issue with opening up the caliper to exchange wheels, the dual pivots have no integral quick release. The Campagnolo eccentric cam was a terrific design.