I got the P-car bug late last year. Sold my Z4 Coupe and got a 911. The 911 is amazing - the realization of a boyhood dream in many ways, but I will always miss the Z4. I wish I could have kept both. That said, there's nothing like a Porsche and your choice of the new Cayman is shaping up to be something quite spectacular.
Personally I would wait a year or two and get one used. I was thinking about a 981 Boxster, but every time I configured it the way that I wanted, I was north of $80k. Porsche cars devalue like a mofo during the first few years. I picked my used 2009 911, with warranty out to September 2015 for over $30k less than sticker. I get to drive it for a couple of years with peace of mind and then if I am done with it I'll be able to sell it for $5-10k less than I bought it. That's a hell of a lot less than the new car depreciation would have been.
Good luck with your choice though. Life is good when you are in a position to get one of these cars. I am sure you have done your homework, but if you haven't seen these reviews make sure you watch them asap. The new Cayman look phenomenal.
And here's a pic of my new girl just to finish up.