Yes, it is certainly possible to re-blue the slide with a high polish finish. Brown offers such a high polish finish, too. We don't see it a lot here but I'm sure there have been some photos taken. Turnbull's finish is obviously top notch.
What is the "default" material for Gen 3/4 Browns? I bought a stealth gray Special Forces in 2012 (through Jerry), so I'm assuming it is Gen 3. I never specified either way, but I am curious if my gun is stainless or carbon. I ask because I am considering having it blued to a high polish in the future. Thanks in advance!