The only thing to worry about is making sure the coating used on the hanger doesn't react to the finish...
Put them on stands or in their cases. Nothing good can happen to a guitar hanging on the wall. When I see a guitar hanging on a wall, I always think, "Look at this poser trying to show everyone that he has a guitar. Must not be able to play it." All the players I know, have them put away or on stands unless they're playing them. If anyone's interested in seeing them, you can always break 'em out.
Only problem I still have is what to do with 4 hard cases?
I have all of my regular players hung up on the wall; the only one away in it's case is my acoustic. I play them almost daily.Put them on stands or in their cases. Nothing good can happen to a guitar hanging on the wall. When I see a guitar hanging on a wall, I always think, "Look at this poser trying to show everyone that he has a guitar. Must not be able to play it." All the players I know, have them put away or on stands unless they're playing them. If anyone's interested in seeing them, you can always break 'em out.
I prefer a hanger to stand because it's 100x easier to knock a guitar off a stand then it is off a wall.
I use both. I have a rockstand that holds 7 guitars for my fav's and I have 2 hangers by Hercules for display.