I have both cars and the Carrera GT is faster than a stock Ford GT. The Ford is more fun to drive around town. The clutch (ceramic) in the Carrera GT is very sensitive, this makes the car harder to get off the line without stalling the engine.
All I want to know is when the fun driving the GT stops. I've had mine for about 2 weeks, put almost 3,000 miles on it, and still can't wait to get back in her.