Well i've pulled them at 190, 195, and 200. I like to render as much fat out as possible so you could go to 200 with no ill effect to the butt. I like the ones taken to a higher temp 200 better than the ones pulled off at the lower temps. It just breaks down more of the fat and such and is very tender. It'll be good no matter what temp you decide on. As Doug said the temp will still climb after pulling it off and it will still continue to cook for a little while wrapped in foil and resting in the cooler.