I am happy with most setups as a dualschock driver too, but some few won`t have a huge effect or any in some cases.
A common goal of most setups is better handling (obvious isn`t it? ^^) sometimes with a drastic change of camber settings.
Unfortunately a joypad won`t let you steer as much as you want, steering is limited - a higher speed results in smaller steering radius for better gameplay.
With this limitation you can`t take full advantage of a setup sometimes but you will notice a lower speed and acceleration on straights.
At the end a good setup will always improve a car no matter how you control it.