Z06's don't have a carbon fiber roof. However, there were some roof seperation issues with the 2006MY.
Changes to the 2007 to 2008MY~
1. Moved from the T-56 transmission to the T-6060. Some say, this was a bad move.
2. Steering rack has been improved for "feel."
If "mileage vs. wear" is an issue for you, then take a look @ General's tire in Z06 sizes. If you're wearing the inside of your fronts, then get your camber/toe adjusted. Chevy spends 90 seconds getting all 4 wheels aligned. How good do you think that job is going to be? Their "within spec" parameters are about as wide as the Pacific Ocean. Seriously, get an alignment, and specify you want it set up for maximum tire life.