I've never had to migrate large projects over to 64b before, but it does take some effort in most frameworks. As with so many things in software development, its likely just a matter of priorities. Unity 4.2 was released quite a while ago, and it was rather solid not long after. In situations like this the best motivator (after technical obsolescence) is user demand. I'm still quite new to KSP, but i'm already hitting memory walls thanks to the wonderful add-ons the community has contributed. Migrating to 64bit would be a lot easier than implementing better resource handling, which would also be greatly appreciated. +1 OSX 64b Unity standalone please