Comment 6 for bug 1481170

Once an effect produces sound independent from the input signal it can safely be stopped and continued afterwards. So here is no settling issue. There might be only an settling issue issue for the first start if there are internal filter need to setup.

From the technical point of view a three state button will work, but I am afraid a three state button will not fit to the way people are using effects and it might be hard to visualize the third state with a single LED.