I'm running KVR's and am happy with them from the point of view that they are perfectly good for the street, and hold up well in autocross. I am sure I could get more bite out of my brakes with a more aggressive pad, but I'd rather have better rotor life at this point. Cold stops on the KVR's are just fine on the street.
Hard for me to tell how much difference the pad change made by itself, as I went to bigger rotors and calipers at the same time.