Another clarification,
Server transfers will work in this order:
PVP → PVEC → PVE → Unofficial
Meaning, you can transfer between the same level or to a level below. But not from below to above. Meaning, a PVP player can transfer to another Official PVP server, or to any other mode. An Official server PVE player, on the other hand, can transfer to another PVE Official server or to an unofficial server, but not to an Official PVEC or PVP server.
There will be a lengthy announcement with all the details about this feature once we’re nearing the launch, as we mentioned in the patchnotes.