The 7AT is smooth when you want it to be and sharp as tack when you put you foot down and use the paddles, it has rev matching on the down shift similar to the manuals, best of both worlds and suits my needs where I am now. Have owned a MY08 350z Track Manual and it was great car but the time was right for an auto.
Drive both transmissions from the dealer over the same road for an hour each in all types of traffic and roads, you will know which is right for you. Go in with clear head either way the 370z is a great car.
Best of luck in your decision.