It does nothing to help with subject movement. With practice you can learn to shoot at some pretty slow speeds. Lean against a wall or tree. Keep your feet half a meter apart. Tuck your elbows in against your body. Practice moving the tip of your arched index finger straigt up and down on the release button while nothing else in your hand moves. Go to a drugstore with an automatic blood pressure machine and practice breathing techniques, calming yourself, and see just how low you can get your blood pressure and pulse. Take a course in pistol shooting. These will all work with any lens, any camera, even with dead batteries...LOL I sure hope that Leica doesn't decide to turn M lenses into oversized monsters full of iffy electronics.