I have the KitchenAid Professional 550 HD which I've had for probably 10+ years and I love. My flat beater is metal and not coated. I will say I don't use my mixer that often like most people. I'm now finding that black dirt is coming off of my flat beater. I tried washing it by hand and then put it in the dishwasher but neither made any difference. I need a new beater but looking at the reviews this coated one may not be any better.