well as an owner of a 2007 C6 Z51 vette and a 1983 911SC Cab I can tell you that the vette is definately faster!
I love the power (mainly the torque) of the Vette, its addicting, but my 911 is so much more fun.
Its more fun to drive a slow car fast than a fast car slow. The sounds of my flat 6 are awesome. The C6 is very modern, which is nice for AC, but when I am in the 911 I cannot imagine leaving the Porsche family....