...I attached a 6-stop example. If you look close, you'll see that the ASA 400 film (left) exposed at EI 6 (right) gives more shadow detail and shows no degradation in the highlights. Overexposure is no problem, but you may notice a slight increase in grain with 35mm film.
Ralph, No offense but I disagree there is "no" degradation of the highlights. Even on this monitor I can see some highlight compression. Not bad but I wouldn't make a habit of overexposing.