The small burn pot is covered with a large deflector plate that absorbs the heat and spreads it out below the cooking surface making them essentially wood-fired convection ovens. Flare-ups are a thing of the past. You need to keep the plate clean because it is right below the food and if you leave sauce and grease on there, it can smolder and leave soot on your food. Carbon buildup will also diminish its heat transmission.
I've been using a pellet grill for a LONG time (Traeger for ~15 years?), so I know an upgrade when I see it. I just picked up a YS640, and it's amazing. I love removing the diffuser, adding the Grill Grates, and doing so nice searing! My first cook was a batch of rid eyes, and they were both beautiful as well as delicious. My "guest list" of people wbo want to come over for food keeps growing... Nice problem to have. Good friends, good food, good times.
Brad Barrett at Grill Grates makes a fantastic product. Reverse searing 2″ steaks and chops (or thicker) works great on pellet smokers as you can get the internal temp up to 10-15 degrees below your desired finish temp, remove them and loosely wrap / cover in foil, crank up the smoker with the grates on to say, 400 degrees, and then sear off your protein getting great grill marks with little to no sticking at all. Huge fan of Grill Grates.
With 341 square inches of cooking space and a digital control board that sets the temperature from 180 to 500 degrees, you’ll be cooking whole meals in this grill, even though it’s the smallest model that Pit Boss makes. It will hold up to a dozen burgers for parties, or a chicken and vegetables for the family dinner. When cooking is done, the porcelain coated grill grates are easy to clean.