Th V-6 will not drive fast like the GT will. It is a different feel.
However, the 2011 you get the updated styling, the vastly improved interior, and you can get a V6 track pack that will the GT suspension on it.
One thing you could consider is if you got the V6, the aftermarket will be hot for it with the new motor. A SC or turbo kit will put it past the 2011 GT horsepower if you care to go that fast.
If your decision is based upon the V8 sound and nasty torque, then the 05-10 GT is your car. I guess the 2010 has the new body and interior too. My vote is for the V8.
If it is more about the interior quality, new body the newness and the hype of the new drivetrains, then the 11 is your car. 30 mpg too.
In the end, what I would really do is the greedy thing, and spend 5K more and get a 2011 GT from a dealer that will sell it to you at invoice ($27,300+).