I always use clips for squats. Not because the plates move that much without them, but because I can picture in my mind what a megafail it'll create if somehow one plate falls off, and I tilt to the heavier side, then all those plates fall, then back to the other side for the remainder of
those plates to fall, and somewhere in there I fall over the safety bar, spraining my knee and impaling some poor kid on the bench press with the bar.