The CSR I usually rub and WSM for a couple of hours, then foil with some BBQ sauce and cook another hour. I don't try to firm them up, just take the foil off the pan and serve them in the sauce.
Because pork loin can be dry, if I cook on the grill they go on the rotisserie for as little time as possible.
Most of the time I slice loin thin and cook sauteed and simmered in a sauce. Some favorites are a wine, cream and mustard sauce, a white wine cream sauce with tarragon, or sometimes an apricot sauce with pine nuts served over polenta with onions in it. Simmering in the sauce tenderizes it and keeps it moist.