Nothing wrong with 370Z 7 AT.
I own both 370Z A/T and 300ZX M/T. They are both awesome, but act and should be treated differently at time of driving.
I drive both of them hard and push both of them way past 7500 RPM occasionally.
370Z in Manual paddle/tip tronic mode does not up shift for you. It only downshift for you but wait for a very long time to react. But, hey it is faster of the line than most racers can shift through gears. It has pros and cons.
Less responsiveness when you want to race your car or try to power slide and drift it.
300ZX 5 speed M/T is a definitely different story, it requires more respond and input, but a lot more fun to drive AS LONG AS t THERE IS NO TRAFFIC LIKE IN SEATTLE, running between 1st - 2nd for hours. This could be really suck.
I decided to get A/T for my Z34 because of couple reason.
1. My GF can also drive it without worry about rolling back down the hill.
2. If I go on a long *** ride with heavy traffic, my back and my knee don't .itch about it after I get home.
3. 370Z auto give you a plenty of fun without engaging the clutch which in new era now. Forget the 19 century technology. We live in a tech world now.
Summary: buy what suit you and your situation is the best decision, good luck.