If you have no idea (like me) what size KitchenAid mixer is sufficient, and what size is excessive - I can tell you with certainty that a 300 watt mixer will struggle with a kilogram of wheat flour in pizza dough.

I can also tell you that there is something on the underside of the mixer that can lacerate your finger, when you wash off the bits of dough left on the mixer (if mixing a bit too much dough, perhaps).