I have this and the K45. When I was in pound cake production I would have both going side-by side on the counter so that I could put two Bundt pans in each oven at the same time until I had 8 cakes baking. The batters that each produced could not have been more different. The cakes came out the same, but the whisk beater on the K4 produced a batter that was pourable; it flowed. I guess you would say it was thinner. The batter from the K45 with the paddle beater had to be coaxed out of the bowl with the spatula.