can confirm this isn't the final release.. it still says "BETA" in the about this mac screen
Apple I think always does a GM Candidate for Mac because we always have to download the final installer no matter what. I remember it every year now. The GM Candidate just allows it so we can submit our apps as Dev without getting the whole you are running a beta, please use the latest release to build your apps message in iTunes Connect. I can't remember there ever being a straight GM for the last 3 years atleast. And last year there were 2 different GM candidates and the build number was one digit more on the 2nd version. The Beta branding will go away when you install the final release version.