[Lucid:]

Because no other NPC currently has a background, I don't think I will take backgrounds into account. If the background has no effect on the avatar, but the avatar was winning material, I would simply strip the background off the avatar. However, if the background is important to the overall look of the avatar, such as if it hides part or all of a back layer, I might leave it on.

In short, for consistency's sake, don't use backgrounds unless it's important to the layering.