I have had the 6600 for about a month and a half. It has the same start/stop button. I have a very bad ankle and both knees are bad. I am still learning to use the start/stop button and have put the pedal clear away. Not only is the start/stop better for my legs, my lower back appreciates it as well. It takes a lot of getting used to, but it is worth it, even in FMQ.