Hehe... Saw this post, earlier, and waited to chime-in, to see how it played-out! Funny thing about butts...they climb really fast, at first! I threw an 8 lb butt in the 2D at 3 a.m., Sunday. I went back to bed and got up about 7; it was already at 155. I just looked at the smoker, smiled, and went back in to drink coffee.
Next time I looked, around 9, it was at 160. It remained at 160/159 for the next 4 hours! Hehe...thought you were going to fool me?? ;D ;D Long story short, the stall eventually broke, and started climbing, and the butt finished on-schedule, after 13 hours.
Moral of the story: Large cuts will always stall! ALWAYS! It's just the science behind the cook that you cannot control. So, rule #1: Don't panic! You will never smoke a pork butt at 225-235 and have it done in 4 or 5 hours...never!
As for the hold: If, for some reason, you do have something finish way ahead of schedule, double-wrap in foil and pack in towels in the cooler for up to 5 hours. Anything longer, cool the smoker (with the door open), set to 140, and place the wrapped meat back in there at 140. You can pretty much hold it indefinitely, like this.