Item 5 is incorrect IMO
On two accounts. First; what if you need to charge several devices at the same time?
Second; although I agree that it is important to keep your luggage to a minimum I think its even /more/ important to keep your battery powered devices healthy. Your charger is more than a simple power adapter. For example; charging your phone using an adapter is likely to provide better results than if you charge it using an USB port because unlike an USB power a charger doesn't provide a mere endless stream; it checks the status of the battery and usually changes the charging characteristics based on that.
As such; I think you're much better of sticking with (several) charger(s) so that you can be sure that the charging is performed in the most optimal way.