One non-server related issue this test has revealed is that the dev team may have overlooked some older quest content bottlenecks when you have a lot of players present that should be remedied. For example, My Feisty Little Chocobo's quest objective of killing 3 Brood Ziz was a nightmare with lots of people camping the small area for the mobs, and their respawn rate was slower than that of other nearby mobs. Normally you don't have such a high concentration of players in older content like this, but when it becomes an issue it's frustrating.