Malcb - we've already swapped the 350z and the crossfire for a comparison. I love the Nissan, it feels really quick through the gears and has a wonderful sound. I would say it's about 5mph quicker than the crossfire on the straights, and fairly evenly matched on the twisty bits. My colleague thinks the crossfire is wonderful, particularly the looks, the ride, and the sound. At the end of the day they're both fairly quick, enormously fun cars, but very different in their character. I couldn't imagine driving a 350z every day, just as my colleague wouldn't settle in the Crossfire. The Nissan is the track car, the Crossfire is the fast continent eater. Plus I can drop the top during the occasional sunny day - and that's priceless!
A guy has an Audi 225 TT at our company and again it's a fast car, its interior puts the Nissan and the Crossfire to shame, but it just lacks the involving drive in my opinion. I also tried the S2000 and disliked it as a car, but loved it as a little racer!
What my colleague with the 350z and I agree on is both cars are better than we are as drivers at the moment - we really need to get to know them to get the best out of them - we both have a terrific drive to work - twisty country lanes mixed with longish straight 'b' roads, and neither of us has yet even started to tap the potential in the wee beasties! I've had one pretty scary experience so far on a road covered in cow muck - the following corner seemed to have every wheel going in opposite directions - how I'll get on during the winter is anyone's guess - I crashed a Land Rover into a drystone wall during last year's limited snow!