I usually pull mine around 185. The relative doneness, I think, has to do with how slowly you get it from the first temp peak (around 165 or so) back to your finishing temp. This is where a fire at 225 or one at 250 or 275 makes a HUGE difference.
When you pull it off the WSM, foil, and add to the cooler it's going to rise in temp ~20 degrees, and then sit there for hours. So there will be plenty more cooking going on until you unfoil and put on the cutting board.
BGE - Med, 22" Weber OTS - 2010, 18" Weber OTS - 2001, 2 x Dual Layer UDS