The difference between the 642 and the 442 is the color of the paint they use. The durability is that of any paint. Most of the air-weights sell for under $400. For that one gets a reliable handgun with a lifetime warranty from a reputable manufacturer. They are meant for concealed or holstered carry and hard use.....not for lookin' pretty. If you want more durability spend another $250 for an all stainless model.

That said, it seems that the response S&W gives to most folks with these firearms, is that they will, under warranty, refinish the gun one time.