I took Jeepster's advice and loaded my large to right below the top of the fire ring and I am right at 12hrs @ 250deg and she is holding steady. I recently replaced my firebox and I am not so sure that BGE didn't possibly slightly redesign the firebox. My old one was 15yrs old. In any case, I pulled the boneless half of my butt off at 190 and she is resting. Based on what I can see below the platesetter, she still has a LOT of lump left.
Thanks again to the Jeepster for doing the research and sharing with us eggheads.