Having the adjustable roll center feature on the front and rear of the car enables one to adjust the roll centers of the car accordingly !

Lower roll center (further away from the CG) permits the car to roll more. This means more grip on that end where the roll center is low. But more grip can mean more sluggish.

Higher roll center (nearer towards the CG) will resist the part of the car from rolling. This can mean lesser grip but can also mean the car can react faster in and out of corners.