I agree that the engine would appear to be in the wrong place hanging over the rear axle, but Porsche ingenuity of engineering makes this layout handle beautifully.
...and yet, their relatively recent MR platform out-handles it. Like Honda and Mini and the FF platform, Porsche has done amazing things with a platform that, on its face, should handle like a pig. HOWEVER, when all other things are equal, cars still handle the best when the engine is between the axles.
Imagine what a Cayman would handle like if Porsche took the decades of R&D and millions (billions) of dollars it's poured into its RR platform development and spent all of that on MR cars?
That's not to say that MR is better in every way than RR. Fitting four seats in a Cayman would be quite the trick, no? But if you're after beautiful handling, and all other factors are equal, MR is the way to go.