My opinion:
1) I think vinyl tops are ugly on E-bodies. Like said before, it breaks up the flow of the car. I don't really like vinyl on any car, for that matter. I'm also 26, so maybe I'm too young to like it....
2) I wouldn't want it for the rust factor. Even with paint under it, I would still worry about rust. I know it prolly wont ever rust under there, but I would always worry about it and probably keep checking underneath it, and you can see where that would cause other problems.
Just my opnions.