Normaly I drive in S mode in the city, i like my car to be reactive, and the shifting happens at a higher RPM's. When I'm on the road, I use D mode and the car is smoother and it saves gas.
But when I want to go sporty I use M mode and I change the gears when I wan't, the computor will no allow to over rev so there is no danger to break the engine and I personnaly like to be able to down-shift and use the compression to slow the car.
I'm now anxious to install my CAI and Solo Performance Mach X-LLT J-pipes exhaust, with M mode i'll be able to hear that beutifull sound, even if it's a V6.