The NP3 finish is unique in that it provides additional lube built into the finish. Robar says that after an initial break in you can actually run the pistol dry. But what impresses me most with this finish is how durable it is. I had my full size M&P9 and 9c done years ago and they still look like new. The Melonite finish though good shows holster wear quite rapidly, with NP3 holster wear is virtually gone. Also cleaning is greatly aided, not only can you see any carbon buildup easier it just wipes away with this finish. It is expensive but you get what you pay for.
As far as the action that too benefits from the increased lubricosity of the teflon impregnation. All my M&Ps have better triggers now as a result. I even did a couple Beretta PX4s in this finish.