Costume Gears: Usable or Unusable in GVG areas?

[Aaronock]

Despite not really pvping much these days, I still think its a game aspect that everyone can see when you are switching around certain headgears. Granted, sometimes you could be switching between two of the same thing, but this is still an important aspect of gameplay to even deduce that sort of junks.

So would it de-equip your costumes similar to how your pet is put into its egg when entering PvP/GvG zones?