Not sure of the correct terminology but if you have a piston pushing on a pad with a big area it will put less force on the disc than a smaller pad.......ie its the same force but over a smaller area...depending on the qualities and operating temp of the brake pads the smaller one could perform better as i guess it would generat more friction and therefore heat..the larger discs will dissipate heat away more quickly than smaller ones keeping performance more consistent and reducing fade