Default is 480 - safer editing build.prop. density apps can cause issues and problems.
Sent from my CM11 Kitkat powered N9005
ROM Toolbox Pro shouldn't cause any problems. I've been using it to change system-wide dpi since the day I got the phone, without issue.
That being said, some of the stock apps just don't play nice with custom dpi. The solution is to change system-wide dpi via the method of your choice, then use App Settings (an xposed module) to manually change problematic apps back to the stock dpi (480). If I remember right, the ones you need to leave at 480 are phone, contacts, calculator, and gallery. I'm not sure about the stock launcher, as I don't use it.
Alternatively, you can use modified versions of those apps that have been made to work with custom dpis, but you'll have to search for those, as I don't have the links handy at the moment.
Sent from my SM-N9005 using XDA Premium 4 mobile app