I am seriously considering purchasing a 442 or 642 for pocket carry in the summer. My everyday carry is a Ruger SP101. I love the gun but it is too heavy and bulky for pocket carry. I normally carry inside the waistband. With hot weather naturally I dress in lighter clothes and my holster won't work very well without a belt.
I usually prefer stainless but the aluminum frame of the 642 doesn't look as good to me as the all black 442. How well does the finish hold up on the 442? I sweat puddles here in the hot humid south and my sweat is toxic to blued guns which is why I avoid them. I know the frame on the 442 is aluminum but I am concerned about the steel parts. I will be using a pocket holster which should help and I will keep it as clean as I can but if the 642 will hold up better I will get it. My local gun store has both in stock and neither have the lock and the price is the same.
Stainless steel is better than carbon steel when it comes to resisting corrosion due to human perspiration. For body-contact concealment the 642 will always be the better choice. This is not to say one cannot make the 442 work....it just won't be as seamless.
As long as you give the gun a good wipedown and oiling after carry, a 442 will probably do fine.
And YES you are RIGHT to doff your massively overbuilt Ruger for the much lighter, more compact Smith!
My 642-1 PRO weights 14.5 ounces, takes a 5-shot "en-bloc" clip of rounds, and fits EASILY in my front jeans pocket!