I have used on/off when fmq. I am a relative newbie to quilting having only taken an interest in quilting since 2009 and my "proper" machine being a janome 6600p last year for christmas after using a modern featherweight machine in case it was a passing whim. I like using the on off button because for me, it takes care of keeping the speed of the machine constant. I don't know if I would do it different if I had learnt with a machine without the off/on button ?