-G35C has longer wheelbase
-G35C has softer springs
-350Z has 7 more horsepower
-G35C has a decent trunk and back seats
-350Z is 200-something lbs lighter (depending on how they are configured)
I would (and did) take the G35 Coupe over the 350Z. I took it because of the styling, the luxury, and the increased practicality. I feel the performance sacrifice is worth it if the car is going to be your daily driver (especially since I don't feel like I "sacrificed" anything.