Re. the speed issue; nobody has mentioned the fact that on the Airbus in managed descent mode, the speed will sometimes vary a bit (if the winds are different to those forecast/entered) in order to stay on the correct descent profile. Our SOPs state (and common sense suggests) that selected speed should be used if ATC have assigned a descent speed but that doesn't stop some pilots (who think they know better) to leave it in managed rather than use the speed brakes.