Duck stance refers to the angles of the bindings. So a typical duck stance would have angles of about +15/-15, or some variation of that. It depends on whats comfortable for you. If you look at the bindings, they are both rotated out, kind of like how a ducks feet are angled out and it makes them waddle. The reason this is good for riding switch is because no matter which way the board is facing, your front foot will be angled in that direction, which will help you control the board. This is typically a park setup. If you don't plan on riding switch, you don't need this. However, I think it's just more comfortable this way anyway.