I have the HP+ pads on my WRX now. They definitely rock wrt stopping power. However, they do make noise (bit of a grating noise and some squeaking) when braking. If you come to a stop at a traffic light, people will notice. It doesn't bother me much, but it might bother you. On my other car (Lotus Elise) I have Ferodo 2500 pads, and they are basically silent, other than the occasional squeak. Once I'm done with my HP+ on my WRX, I'm going to try the Ferodo 2500s.
IMHO you never can have enough stopping power.