Still seems like the GXP rotor would be the best bet since the hat on the CTS-V rotor is too big to use the parking brake shoes unless we use CTS-V parking brake shoes so we have a functional parking brake. The CTS-V rotor is more shallow than the GXP so that may be why the CTS-V rotor was used, so the bracket wouldnt have to be offset too much - sound about right?