To be clear - there are 4 levels in the KK: Upper, Main, Lower and Sear (upper grate upside down on the charcoal basket handles).
Upper: pizza and spatchcocked chickens.
Main: Almost everything
Lower: Normally where I sear meats. Main use is it's covered with foil as the heat deflector for indirect cooks on the Main and Upper grates.
Sear: I rarely use this setup anymore. I can get a good sear without worrying about over charring the meat on the lower grate. YMMV