A fully integrated bike control would involve down shifting and the use of both brakes at the same time. I found myself doing this today without really realizing it. The chief rule of down shifting is not to cause an unplanned lock up of the rear wheel or any such force as to loose control. Even down shifting letting out the clutch abruptly in a turn could cause a dangerous destabilization of the bike. Be smooth.
I do like to touch the brake when a ridder is following closely to alert him of my speed reduction . Smooth and safe.