This is what 3 yrs of lurking in the cookshack forums does ...
After 3 yrs of lurking and 4 years of researching, I finally smoked a prime rib.
Bone in Prime Rib 7.5lbs
Cooked @ 250 until internal temp of 110 degrees.
Lowered temperature to 140 degrees (without opening the door) until internal temperature reached 120.
Opened door for a few minutes and left for 4 hours.
Final result = internal temperature of 134 degrees.