While I believe the 911Turbo is a superior car, you gotta give the guys at GM the award for "Minimizing cost, maximizing performance/fun." (A philosophy I adhere to myself!)
A Z06 costs less than 50% of a 911 Turbo, yet when it comes to performance/handling/fun ...etc, it probably offers 75-80% of what a 911 Turbo offers.
Not a bad trade-off if you're not rich.
However, there is one thing the Z06 does not have that the 911 Turbo has: exclusivity. And that's a big reason people buy 911 turbos and Porsches in general.
Just my $0.42.
-Z-man.
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My toy:
http://www.pelicanparts.com/gallery/Z-man