I have the 6600 which has the same start stop button. When I do FMQ i always use the foot pedal so I can stop in an instant and exactly at the right spot. i was taught by Harriet Hargrave to not take your hands off the quilt until you are stopped. Therefore I like to keep both hands on the quilt and not take one off to push the button. I also find the needle up down and the knee lift a great help with FMQ.