Given the amount of complaints I see from people who lose their stuff when they die by there own fault, I think having this PVP switch in the normal world is a bad idea.
Theres always going to be the poor sap that forgets to turn it off after a PVP match en he will fall victim to 'sitting duck' hunters.
Then the discussions start and they never end friendly.
Keep PVP in a separate world, when people enter they know what there getting into.
It wont change a thing either, when people now dont go into the PVP world, what makes you think they will switch PVP on in the normal world ?