By the looks of it you've almost had everything that could go wrong with a Z as in the most common issues.
I think if you hang on to it you should be able to put plenty of miles on it and really enjoy a trouble free car.
I wouldn't blame you if you still feel the same and you just want to move on.
I have an early build Jan 09 in fact and knock on wood I have not had any problems with it so far.
I still believe the majority of 370Z's are trouble free but there is small fraction that we have come to learn have had issue as you have experienced a lot of unfortunately.