Edit: I take back what I said about kind of agreeing that the idea was not real good for players. The idea is pretty cool, but I think it should have different criteria than a PvP flag, such as you can tp away or something, to make it slightly more balanced.
Anyways, as I've added it to redmine, we only really need to figure out how it's going to work exactly, and whether or not your description of it will be used in its final implementation.