As a SCCA racer, PCA HPDE instructor and 911 specialist I feel qualified to comment re: GT350 vs 911. The Shelby GT350 is in fact a world class track car on par with a Carrera and possibly the 991 GT3. The overall handling and braking, suspension, and power combine to create a very balanced and predicable package. On track turn in, mid corner stability, and full power track out off a corner actually feel more stable than 997 generation GT3's. The big difference between 997 GT3's and the Ford is the fact that the Porsche is a race car, lightly disguised as a street car. They are amazing, but not for everyone. The inexperienced 911 driver can get in real trouble fast as the rear weight bias makes driving different. In the the hands of an expert, they fly.
None the less, can't wait to put the 350R through her paces on track!