I've been on Star Tours so many times, always make a point of riding it every day I'm at Disney, and sometimes more than once a day. I've sat all over the place in the thing, and you know, sometimes it does feel a bit rougher, but I've never particularly noticed it being rough at the back. I think it depends how you sit, and how you allow yourself to be thrown about to be honest. You can brace yourself for the movements, or just ride it out, in which case you can really be thrown around, whether you're in the back or front. I sat in the front row last year on one go, and it was awesome, and was really jolted about.