What a shame. The fibreglass ones are the best to drive.
I used to believe the glass cars were 600 pounds lighter, because thats what everyone said. That would make a HELL of a difference and would definetly be worth the premium. But after seeing a few people actually weigh these cars, that's not the reality. As long as they weigh the same, have the same power output, gearing, suspension, brakes, etc., I cant see how they would drive any differently.
Regardless, the glass cars will always command a premium, and will appreciate the most over time, simply because they came first, and are among the rarest. If your looking to drive, buy the cheapest and best car you can, and it will be steel. If your looking for more of a garage queen, the glass car would be a good choice. If you have unlimited funds, none of the above really matters.
Another option is to build a GTO clone, but please, only choose cars that are in rough shape/damaged/burned. I am seriously surprised no one has built an F40 clone from a 308, especially seeing as the 308 shares the shares the same basic cabin structure, windshield, rear glass, side glass......I know, the horror.