I think the worst thing about stainless rifles is that people have taken that to mean they won't rust, that you can use them in the rain with impunity, and they don't need the sort of care other rifles need. It isn't so.
The stainless used in rifles comes in different grades. Barrels are usually 416 or something similar, a grade of stainless which actually isn't all that corrosion resistant as stainless steels go. It certainly will rust, if you don't look after it. A matte finish, such as you might want for the reduction of visibility in a hunting rifle, further reduces what rust resistance it has. As well, if you tear your rifle down and have a good close look you'll almost certainly find there are parts which actually aren't stainless at all - springs in particular, as well as pins and clips and other parts hidden away in the stock.
The net effect is that a stainless rifle will need to be looked after. It may offer some benefits in terms of resistance to bore erosion, and may or may not offer a bit more resistance to corrosion than some of the finishes used on plain carbon steel or CrMo steel, but all of them will need some looking after. There are much better options if you want a rifle to resist corrosion, such as nitriding.
I'm not against stainless, and I do own a stainless/synthetic rifle. I own a lot more which aren't stainless/synthetic though, and they all have survived hunting in all sorts of conditions, including rain, some for many, many years. I think a good coat of wax, on all surfaces, and a tear down and clean after going out in the rain, is a better solution than relying on the dubious idea that a stainless/synthetic lets you off the hook.
