I used the deflector a lot when I first got my KK. I burned a ton of charcoal (full basket gone in 8 hours at 225). It seemed to keep the heat contained in the firebox and limited convection. I now use the smallest drip pan I can find to collect the drippings from whatever I'm cooking at the time. I place it on the rack under the main grate, or on the main grate if I'm cooking on the upper. The further away from the fire the better. My fuel consumption has dropped dramatically, the food is better, and the grill is far more consistent. Others may have a different experience, but this has worked very well for me.