Well if you think that the drag from a dynamo will be more than 2 pounds of extra weight then you're really mis-informed. The so called drag is so insignificant you won't even know it if you were to sit on a bike with one & ride uphill.

As far as US military is concerned... they may have the best technology & budget at their disposal & oh yeah probably most of their equipment will already be 10times more optimized for low power consumption than yours or mine. But then to each his own.