If you're thinking of the Cayman R you should also look into the Boxster Spyder.
I drove the Spyder at the Porsche World Tour I was invited to last year and I really liked it a lot.
Too bad all the cars we drive were PDK's... It seems that in previous work tours they would go through too many clutches so now all cars are PDK's.
It's a tough choice between the Cayman R and the Boxster Spyder although a new body style is coming out so you may have to wait on that one.
I really disliked the 911's on the track. They really felt too weird. I really felt that the front was too light and all the weight was in the back. They require a different driving style that is completely different from any other car.
If you can get a Cayman R or Boxster Spyder and get maybe 50hp in full bolt ins I think that would be a damn fun second car. I wouldn't have any of them as my main cars just as second cars.
2012 E92-M3 Space Grey on Fox Red, DCT
2011 B8 S4 S-Tronic , Black on magma red