Reverse searing is one of the best things I've learned having the grill. Its ruined my wife and I for going out for steaks, but oh so worth it.
I have the temp at around 325 during the smoking portion of the cook and don't flip at all. Then I take the lid off as the meat is reaching about 110 and stoke the coals to get it hot then sear for about 20-30 seconds per side.