Discussion on aim stances,

[Destiny@Work]

You would have two buttons/best mousewheel for raising aim/lowering aim.

For shoulder aim, no 3rd person there, you just look over your barrel, which makes it better than the actual used hip modes, but not as good as ironsights.

For waist mode, thats why i said I dont know to which degree it can be realized, but in real life you would look on your weapon, giving you only a vague idea where you shoot, ingame it cant be realized i fear, but it should be lower than actual hip modes.