It sounds like those who have been begging for a year for some form of open world PvP will get that, and those who want to grind rep without doing any PvP will be able to do that. The dev blog points out that only the Southern Shelf missions are tagged [PvP], implying that there are other missions that require no PvP at all. But if you do take the PvP ones, then apparently you'll have slightly easier PvE objectives you can complete while in the Southern Shelf area. From how they've described it, I can't see any reason for PvE-only players to feel left out, and the PvP players will finally get something they can do other than wait for queues to pop.
Eh? Game runs so much better than it did when 1.1 Illum came out, past events and their pvp areas have shown it handles so much better. Fleet runs like crap because of how many are on it and more on it than ever before since f2p, but it still is running better than it did back in 1.1
Also Illum had a population cap on it placed to keep performance up, I assume that is still the case for the event.