I'm big on separating needs and wants, but I do believe that I NEED an extra bowl for the KitchenAid, because when you have to beat both yolks and whites, and then fold, you end up using both the KitchenAid and the hand mixer, as well as three bowls, though I can't quite explain the three bowls, and it seems like it would make so much sense if there were just two bowls for the KitchenAid, though