Well if anyone wants my ten cents worth.... The Porsche is the better car in pretty much every respect, and this is reflected in the price. However it is a well known fact that Porsche purposely held back with the design and performance of the Cayman so to not encroach on the carrera market. For this reason i can't help but think you're buying a car that isn't as good as it should be and lets be honest, will always be seen as 'couldn't quite afford a carrera'. Still a beautiful car though, just not where i'd put my money. Also, maybe a superficial point but i just don't see porsches as 'cool' cars anymore. My uncle has an £80K Carrera 4S with all the bells and whistles and it just leaves me a bit unimpressed for the money to be honest. The TT has never really done anything for me, not sure why, maybe just a bit feminine? Matter of opinion obviously! Anyway for the same money you're throwing at a well spec'd Cayman i'd go for a used RS4 cabriolet, which in my opinion destroys them both in every respect. 'Coolest' car on the planet. Effortless.