Howdy
Just to correct your question. The finish on these guns is not Stainless. In fact, there is no finish on them at all, they are made of raw Stainless steel through and through. The surface is highly polished though, so it is very shiny.
When Ruger first introduced the Vaquero, it was the blued version. When they got around to making a Stainless version, the first ones had a brushed finish to them. However Ruger soon realized that a highly polished Stainless gun looks a lot like the nickel plated guns of old. If you closely compare a nickel plated gun to a bright finshed Stainless gun, you can tell the difference, nickel has a slight yellowish tint to it. There is no color at all in highly polished Stainless. But at a glance, a bright finished Stainless gun looks a lot like a nickel plated gun.
I have a couple of Stainless Vaqueros, 45 Colt, one with a 7 1/2" barrel and one with a 5 1/2" barrel. Like any gun, if you take care of them, they will last forever. Yes, you can scratch them, if you drop them on something harder than the Stainless, like rocks or gravel. But it is easy to polish out any light scratches with a buffing wheel and return them to their factory shiny condition without any scratches. You can't do that with a blued gun, if you scratch it, or if the blue wears, you either live with it, or have to blue the entire gun again. Cold blue just doesn't cut it.
One drawback to a bright finished Stainless gun is in the right conditions you can get a lot of glare off the sun, which can disturb your aim, depending on where the sun is. I also like to blacken the rear edge of the front sight, to make it stand out better against most targets.
And let me dispell one myth before it gets started. A Stainless gun is no easier to clean than a blued gun. I don't know where this myth came from, but it is not true. Ease of cleaning depends on the surface polish of the gun. A highly polished gun will be easier to clean than a gun that has some 'tooth' to the finish, either blued or Stainless. Given the same amount of polish, a blued gun and a Stainless gun will require the exact same amount of elbow grease to clean. And a bright finished Stainless gun will show powder fouling more than a blued gun will. The blued gun will tend to hide fouling that the bright Stainless will highlight.
I like my Stainless Vaqueros, but I usually prefer a blued gun.