I know a person who had their whole M&P cerakoted, not sure whether he had the barrel done though. I had a couple M&P slides refinished via cerakote; as well as, numerous 1911 slides/frames. When done right, and I emphasize done right, cerakote is very effective. It adds just enough thickness to tighten up loose tolerances and for bearing surfaces, like slide rails, cerakote reduces friction once broke in. I've never considered getting an M&P barrel done.