I agree, I think splitting the servers would hurt the current server and likely the new PVE server will not fair well either. I think the best option would simply add new zones (the ones you already have made and ready to go) to make about 50% of the new zones PVP. Change all the current zones and 1/2 the new zones to PVE only.
This allows people to still have the best of both worlds. Clear warning to the people that going into the PVP areas that it's open PVP and full loot.
Example would be.
Add in the North zones 1132 to 1145, 1092 to 1105 (26 new zones all PVP areas)
Add in the South zones 572 to 585, 612 to 625 (26 new zones all PVE areas)
Add the linking zones on the East and West ( 665, 705, 745, 785, 825, 905, 945, 985, 1025, 1065) as PVE zones.
This would make most of the map but 26 new zones in the north PVE. Making the server a PVE server but giving people the option and rewards to goto the PVP area if they want, you could even give rewards in the PVP areas as in maybe faster resource gathering like ZaDocta was saying.
Key is keeping everyone on 1 server, and still keeping them happy. I think most of us can agree that the server PVP state of the game is not really a major issue, but removing tribes to split servers wouldn't be a good either.