I have owned mk1 225 and mk2 3.2v6 tt and now have a 350z. I'm probably not the best to comment on this as the mk1 was the most unreliable piece of crap I've ever owned (mk2 wasn't much better) the only good thing about it was the Quattro, it just gripped and gripped. The 350z is a much better drivers car imho, I never get bored of its torque and it feels like an "event" every time you drive it.
I owned both tts for about a year each and I've had the 350 for six, says it all really.