We should be at 1000 minimum already. Ideally unlimited, since the point of the game is collecting things, but 600 is nothing for a dedicated player to fill. ITL just introduced 15 armor pieces and 12 weapons, all of which we may want multiples to compare rolls and buildcraft. There's also Nightfall and Trials weapons going in and out. Having to vault manage at least once a season to make space for all the new loot is a major, miserable drag and a distraction from actually PLAYING.