Another thing I was thinking about this morning. It's funny how people who have had negative experiences with vinyl tops are often quick to assume that it was the vinyl top that cause the "problem" in the event one does develop after installing one. When in fact it can always be traced back to the installation OR simple fact that there was a problem with the paint work/body work and or prep on the roof area prior to the vinyl top install to begin with.
What made me think of this is the simple fact that if a body guy and or paint shop knows ahead of time that you are going to install a vinyl top, maybe they are not taking the time to finish the roof and prepare it properly "because it's going to be covered up anyway" type of thing. For example, when I had my bird painted I told the guy I wasn't sure if I was going to put a vinyl top back on the car (this was a little white lie on my part because I had already bought a brand new one as well as the cement to install it). However, I wanted to the roof to be painted and prepped etc. just as nicely as the rest of the car. Not too mention I wanted all the holes welded close, ground down and everything flawless so I would be "starting over" so to speak and I knew everything was solid and I had no leaks or potential rust issues etc.
So the bottom line IMO for what it's worth is I believe the trick to making sure a vinyl top lasts and doesn't cause and or create issue down the road is to make 100% sure there isn't ANY AT ALL before you install a top to begin with! Then be sure to install the top 100% accurately and maintain it 100% accurately after it is and it will last and it will not cause any issues and or problems...