I think pulling, chilling and reheating is fine. I would probably do as Marc suggests, double wrap with heavy duty aluminum foil when you remove them from the smoker and place them in a cooler. Make sure you place an old towel or two on the bottom of the cooler, so the bottom of it doesn't melt. I use two towels on the bottom and one over the foiled meat. You can easily get 3-4+ hours in the cooler and the butts will still be very hot.