Shoulder holsters have their time and place. Most people recommend that you get a vertical holster so that if you are open carrying people behind you aren't staring at the barrel of your gun. I don't really see this as much of an issue as long as you are using a good quality holster with the proper retention that minimizes the chances of an accidental or negligent discharge. It's more of a perception thing than anything else. Another objection is that when you draw you may have to sweep potential innocent bystanders before you can aim at your target. Once again training helps. If you want to wear a shoulder holster during the winter then feel free to do so, just make sure you practice accordingly because the draw is quite different from using a hip holster.