Yes, but it's only about 5mm. It's just the thickness of the rotor at the hub. With the DoctorDiff hub the floating rotor sits on the face of the hub, where with the '73+ disks it's flush. The DoctorDiff hub is basically an aluminum version of a turned down 73+ rotor/hub. DionR has a similar brake set up, he just actually turned his hubs from a set of 73+ rotors.
