Keep levels option (similar to keep inventory)

In the Minecraft game options you are allowed to turn on cheats and enable the keep inventory option. It would be a good idea to also add a keep levels option. This option would allow you to only keep your levels when you die and nothing else. This would be a really fun addition to the game, you can play a survival pvp world with your friends and not have to get annoyed about losing your levels. This option applied to a world/server would increase the amount of peoples usage of pvp battles.