I still have to disagree with you. Even though Nissan may have targeted the Cayman as a competitive benchmark for the 370Z (as the GTR with 911), it doesn't mean they reached their goal (unless you take into account price). I've driven them both, and if it weren't for cost (and leg room), I would take the Cayman hands down. Just because they both have the same number of seats, it doesn't put them in the same class.
And let me clarify -when I talk about comparing the Z with Mustang/Genesis/Camaro I'm referring to the V6, not the V8. Specifically I'm talking about the following Comparo:
2010 Camaro V6 vs. Genesis Coupe V6 - Comparison Tests
The only objective rational for comparing the Genesis Coupe over the 370Z (as this was American V6 vs. Import V6) is, as you say, 2+2. Which personally, I think in all practicality is a moot point, because most 2+2 2-door sport/muscle cars have useless back seats.
2010 Car And Driver Lightning Lap Nismo Z hits wall. In 2011 Lightning Lap the Z is absent.
Lightning Lap 2011 ? Feature ? Car and Driver
Lightning Lap 2009/2010 The Z SHOULD have been in LL1 class base price under $30K but it was in LL2 because they used the sticker as the base for the Nismo. And of course the brake catastrophe occurred. The Z is present every year before, and absent afterwards.
Z Meets Wall: We Investigate Why the NISMO Z's Brakes Failed at Lightning Lap - Feature - Auto Reviews - Car and Driver
Lightning Lap 2008: Nismo 350Z in LL1:
The Lightning Lap, 2008 - Feature - Auto Reviews - Car and Driver
Lightning Lap 2007: Nismo 350Z in LL1:
Lightning Lap 2007 - Feature - Auto Reviews - Car and Driver
Just my 2-cents. Can you tell I don't have **** else to do today?!?