Right Chris.
I've read that the '79 280ZX was actually a few pounds LIGHTER than the '78 280Z it replaced. But, like the S30, the S130 also gained weight throughout it's production run.
The real deal on Z's is that unlike most other cars, i.e. the Corvette, the Camero, or the Mustang, the objective of the car seemed to change with each generation. You can argue that the S130 and the Z31 had the same objective but in that case the mechanicals, the looks, and the proportions changed drasticly.
The 350Z has made an honest attemp to get back to the orignal purpose of the first Z car.
The 240's will always have a special quality. And their owners know it. (wink) That said, there's a rather special Z31 I've got my eye on.