the ZBG has only 2 bevels vs 3 on a std CG.
really if ya dont mind scratching/scuffing the blade a ZBG is not hard to sharpen, certainly no harder than a std CG.
FWIW some of the emerson collectors knives, which are not customs, have a ZBG, the ECA P-Tac for one (the collectors assoc P-Tac not the std P-Tac).
i really dont see any reason they couldnt make a production w/a ZBG, its a really sharp edge made for SD but it would work for anything, might chip easier than a std CG though. i doubt he would though it seems more like something for his custom stuff imho.
i have 3 ZBG emersons, the ECA P-Tac, and a '6 and '8.