Once the game uses up 4gb of ram, the game crashes. This wont necessarily be stopped by 64 bit, but it sure as hell will prolong it. Especially when you have 16gb of ram. Ontop of that, grass and tree render distance can be farther with less of a hit. More players on screen, less fps lag in general. This will mostly effect users who have good pc's, max settings was basically impossible in the mmo, due to crashing every 10 mins.
Ontop of these things, the SERVER is in 32-bit, that is a serious serious issue. They are running the mmo in debug mode, consuming like 2x the amount of memory and cpu power that the game normally needs. Everyone's actions are being logged and communicated globally, server crashes will be less frequent and will allow for larger amounts of players in one server. I am incredibly impressed that server 25 somehow survived until 360 players at 32-bit in debug mode, expect 1k players per square in wave 2.
The ONLY downside, and its very minor, is possibly longer loading screens, which can be compensated by: turning off debug mode, standard optimization to code involving terrain downloading. I have noticed that the game is saving a local world, then cross references and downloading the live world when you load in. IMO this makes little sense, as we will always need the live world, and may be better off just downloading the live world only. May be hard to do. Also, we CANNOT be spawning in BEFORE terrain changes are downloaded, even WITH a invuln buff. All in all, the game honestly should have started off with 64 bit, but it is hard to do, fact of the matter is the improvement is a NECESSITY because as it currently stands, you cannot even run their game at max settings without crashing(in mmo).
Correct me if im wrong, but I don't believe it can use my 8gb of vram either. Most likely limited to 4gb as well. (I'm no guru)