With the current knowledge of the car I'd get the Z06 for ease of tuning. It seems like they designed this car with the idea of making aftermarket tuning difficult and generally limiting what you can do with the car. Hell, the Japanese-market car has a GPS tracking system that limits the top speed and only allows you to race the thing at pre-approved race tracks. And then you have to take it in for expensive follow-up service or your warranty is void! The article in Evo magazine said the limiter was at 112 mph on their imported cars and they couldn't do a full quarter mile test. The US cars aren't supposed to have these limitations, but the fact that they did it at all makes me dislike the whole thing. I'd also prefer the lightweight RWD V8 car for its driving dynamics. That said, automotive engineering has reached the point where the GT-R defies expectations and performs like a car weighing hundreds of pounds less. Everything I read tells me that this car is the closest anybody has come to not just making a heavy car fast, but actually making it feel like a light car.
There's still no denying that it's a fantastic performance car and at its price level it is setting a new standard for world class peformance on par with cars costing many times more. Every magazine test has it either matching or beating yesterday's kings of the street in various performance comparisons. Whether or not it is truly more capable is hard to say because it's so much more capable in the hands of an unskilled driver. These magazine guys who hop in the car and are pounding it down a drag strip or around a road course five minutes later rarely get every tenth out of a car; forum guys always beat their 1/4 miles and track times. The most impressive thing about this car is that it just might be giving its all for drivers with no experience in the car where cars like the Z06 require a very skilled driver to wring that last bit of performance out of the car.