Forgot about other factory options.
OP could also research if there are other wheel options offered by Cadillac/GM. I would imagine the CTS,ATS,STS, XTS (inc V spec) are pretty much interchangeable.
Subaru owners do this often: Impreza owners upgrade to WRX factory rims, WRX owners upgrade to STI factory rims, etc.
I've had similar experience with Honda and Mazdas as well.