Steve,
I purchased four butts 6 lbs each and two butts 4 lbs each. All 6 butts were trimmed, fat caps removed as well as bones from meat market in local town. (Harrisonburg VA). THey were netted.
I placed two of the 6 pounders on each grate along with a four pounder. Began at 7pm (Minion method) and maintained 225 to 245 degress for whole cook. Turned, sopped at 12 hours, and at 1 pm next day (18 hrs into cook) I wrapped all butts in foil, and left on at 235 - 240 until 330 pm. Internal temp reached 200 in all six. You never know about the final yield, but I came out with 18 lbs cooked. The smoke was successful and the 45 people it fed was impressed! Total cooking hours was 20 hours, not including the hour to let them rest, and the additional hour to pull them.
Good Luck!!! - David