Here's a system for letting PvPers and PvMers both have their cake and eat it too. Let orgs declare war on each other. Have it be a leadership command, where one org leader targets another and types, /org declare war. The other leader gets a pop-up box saying, "So and so wishes to declare war, do you accept?" You get the picture.
Then people whose orgs are at war can attack each other in 75% or lower zones at any time.
The war would last for two weeks and then it would automatically end (this is to protect against a leader starting wars and then vanishing). There should also be an /org make peace option for leaders, working exactly like declare war but in reverse.
Now people who want to PvP anywhere have that option, and people who don't, can just click "No."