In my experience, pulled pork re-heats very well. I have re-heated it in foil in the oven, and even re-heated it in the microwave with good results. It has enough fat in it to handle reheating without a noticeable change in moisture and tenderness.
Of all the kinds of meat, pulled pork just seems to be easier than most others to re-heat, IMO.
In my experience, the leaner the meat, or the rarer the cook, the harder it is to re-heat, since it was probably cooked to a much lower temperature. The problem with re-heating something like pork tenderloin, is that the re-heating process can end up cooking the meat beyond what it should be cooked to. Pork butt is already completely cooked, so re-heating it won't overcook it. It's not like trying to re-heat a medium rare steak.