Interesting question! I too have been trying to justify trading in the C2S for a turbo. The debate goes back and forth between Yes, why not, to what is the point.
My reality is that is really hard to go fast around Montreal anymore. There are speedtraps everywhere. So the reality is that the true benefit of the turbo could never really be used. Even with my existing Carrera it is hard to let her sing the way she was designed to sing.
The existing C2S is a very fast car for North American roads. In the twisties the car goes like stink. Rev the engine and the sound and performance is intoxicating. Do I want more speed at times, sure; until it is as fast as my previous superbikes, it will never be fast enough.
I have looked at the new Turbo and it is a very nice car. But for now I am on hold. It has everything that I want, but I don't think it offers that magical something extra that will make me trade in my current car. My car has been as close to perfect as any automobile that I have owned. I absolutely love it. If I lived in Germany, the decision would be very easy, but I don't live in Germany and need to keep my license in my pocket. So the only reason that I can see for buying a Turbo, is that I want one. But rationally, I can not justify why I need something I can not really use.
But then again, what is money if you can't enjoy it. If you want a turbo, go for it. I still might if the business has a really good quarter.