I have one of these beaters for the 6 qt. lift KitchenAid mixers, and have used it several times, mostly making chocolate-chip cookies. It works pretty well, though if you start it in an empty/dry bowl, it doesn’t rotate/revolve (KitchenAid mixers use a planetary drive) smoothly against the sides of the bowl. It works better when I raise the bowl with some liquid-y batter ingredients already in it up to the rotating beater; that will kinda “lubricate” the beater edge seals so they don’t catch on the bowl sides.
Want one for my 6 qt Costco KitchenAid. =(