I own one of the first gen twins. It certainly is a fun car, and I lover the super close ratios on the six speed. I am curious to learn more about the new generation, and which parts are shared with the previous gen.
My biggest complaint with my car is the lack of alignment adjustment (camber is not adjustable like it is in a Miata). Many people lament the lack of horsepower, but I went into mine knowing it was slow. I guess it is all about managing your expectations. I'm not trying to be an apologist, because the 1st gen cars are most definitely slow, but if you're expecting this car to have strong acceleration, then you're kind of missing the entire point of this vehicle.
I'm not really understanding the comparison to a Porsche. They are in two completely different price points. If you're discussing new 86 vs. used Cayman, then that is a completely different argument with a different set of pros/cons. The Cayman is a superior vehicle in every aspect, as it **** well should be.