370Zsteve,
Bottom line out of the box the Cayman S beats the 370Z. Yes it costs more to do that. However, while at the track there have been far too many Z's sitting on hot days watching the Caymans roll onto the track. I'd suggest you (A) go out in a stock 09 Cayman S on track and do a back to back run in (B) a stock 370Z. Find a cool day and track so you can complete part B if you haven't added your oil cooler.
For my 370Z track experience on the one and only weekend at the track I was able to get 5 laps before the oil went north. So, $36000/5 laps for the weekend = $7200/lap or $72000/110 laps for the weekend = $654/lap. That's an order of magnitude cheaper on the first weekend. You know what they say about first impressions.
I haven't had anyone from Porsche telling me not to use my launch control nor have they reprogrammed it. And as I've said before under 'choice' I think the GTR is just plain ugly. Others find the Cayman ugly and I personally have no affinity towards the Panamera.
The 370Z continues to be a good bang for the buck. And from there you can go both ways.
As to why I continue to post here I feel the $36000 Nissan entry fee should allow me to write all I want.
Edit: This is in no way intended to offend any of the many people on this forum with whom I have had numerous and meaningful conversations!