I think gear is going to matter more than people realize...
https://docs.google.com/document/d/1...sEohiw2x8/editQ: How much does gear play a part in PvP? Would a healer and dps with full best-in-slot gear be able to sit on an objective and hold off a zerg of players in low-level gear indefinitely?
A: Gear is very important to your effeciency in PvP. The class description healer and DPS don't really exist in GW2. Regardless of that though, 2 coordinated players could hold off an army depending on the gear, levels and play style, of the attackers. It would be very difficult though, do to everyone being able to resurrect.
They've also said because of gear and your level that when you're scaled down you aren't really scaled down exactly to the level that the zone is. For example if you're a lvl 30 and you go into a lvl 5 zone, you'll be more like a lvl 8 or 9 which has a noticeable strength difference over a lvl 5.