Oh thats not bashing...trust me.
One thing I gotta say is that if you are coming from an bigger sedan, the Z will feel a little claustrophobic for a few days (as it did for me), but then you get used to it like you would anything else and you don't notice it anymore. I have a friend that is 6'1 and he has no problems in it...in fact he tries to steal it constantly.
The oil: One could argue that it is a universal problem because everyone has it. The difference comes in whether you are going to be racing it on a track. It can handle just about anything the street could throw at it, so don't worry about that. If you were planning on maybe taking it on the track, then like most other cars, you will have to do a few tweaks; one of which being adding some added cooling for the engine.
As for the G37 vs 370z comparison... We have seen people come and go from here and it seems that if you are in the group who think the two are alternatives, then you are probably better off with the G, not the Z. Seems like you are thinking about some practicality...wont get that in the Z. If you think the Sedan is fast enough, then I think that mayhaps its the car for you
If you go with the Z, then welcome to the forums sir.