IMHO the answer is maybe. OK, depends on number of miles on the brakes, and if the rotors (discs ) are vibrating (warped). As to sensors, if they have not activated (turned on the brake light) then they can be carefully removed from the pad (left front/right rear) and re-used. I have heard that the European rotors are thin and will not turn one time without being out of tolerance. I have a 1988 750 on which I just did pads, I did replace the front discs as they were warped (pulsing on braking), but the rear rotors were fine and not grooved so I resused them (brake sensors reused as well).
One owners thoughts.