First option seems very open to congestion, especially during campaign. During the previous campaign I had to fight with people to pop the Voidwalker NMs but none would like to team up. I can imagine one group sitting there holding the vortex hostage and if three groups do it (or three people soloing) then it clogs the whole zone. I know that probably isn't such a big deal on lower population servers but it only takes three people to hold up an entire NM or else you go into the claim wars.