I'd go with the boxster because the top is removable. The Cayman GT4 sounds great with it's ability to corner very well so you can enjoy the rider but I would just like to enjoy it with the top down.
I would take it on curvy and scenic roads since track isn't really my thing and I wouldn't do it with a convertible. If you ultimately want a car for the track then the cayman would be better with an actual top for more protection in case of a rollover.
Just placed my order for a 718 Boxster S. Exterior and interior color choices were difficult. I finally made my decision to go with something different and went with Miami Blue with Agate Grey interior. Miami Blue production won't begin until July, I was told by Porsche.
I have owned a number of Porsches, from 356's to Boxsters/Spyders to 911's. It's hard to imagine that this 718 S has better performance numbers than the new Boxster Spyder. Despite the flat 4, it seems like quite the car.
Already chosen--Racing Yellow Boxster.
Why?--Having a sunroof on my last car made me realise how much I missed the convertible that Dad had when I was 17.