I own both sets of wrenches and to me, the biggest difference between wrightgrip and Proto is the length of the wrench. The wrightgrip is more of a standard length wrench if there is such a thing whereas, the PROTOs are a longer pattern. The wrightgrip beam is slightly thicker and more rounded making it very comfortable to use. I like both wrenches.
How often are you actually going to use the open end of a wrench to break a fastener loose? I don't do it that often so, the modified non slip open end is a nice feature but, it isn't a deal breaker if a wrench doesn't have it.
