I have a m6 vagon it's the only way to go in a sports car. The only place the auto is better is at a drag strip. And even then I will take being 1/2s slower to know I did the work my self. Any one can go fast in a auto. It takes a driver to go fast in a manual.
The more torque the less gears needed in a manual if the spacing is spot on and I would beleive that the Caddy boys have that pretty well sorted out. As to driving fast with an automatic Jim Hall ran his Chaparral race car with an auto in the late 60's /early 70's, and desert racers are more and more going to auto's. If you live in a metro area and are in stop and go traffic an auto looks pretty damn good. I am driving a CTS V Wagon in San Diego and Las Vegas...6 spd manual. Looking forward to an automatic !