I check my Kitchen Aid and I have the Professional HD. The attachments are metal and I use it to knead dough every week. I bought it at Costco about seven or eight years ago (about $249 at the time) as a gift for my wife, although I am the one who uses it the most. I think, at that time, KA sold the higher end mixer as a standard rather than the many levels of KA's that are available now. In order to get the quality KA that I currently have, you would need to purchase the Professional Level KA that costs around $750 per unit rather than those that sell for $349. I am fortunate that I bought it back in the day.
NOTE: If you look at the dough mixers in any Pizzeria (usually the brand is Hobart), none of them have a hook that is ceramic coated. They are all metal hooks.