I make a conscious effort to spend some time in the drops on just about every ride. When riding into a headwind it really is like free speed. The problem for me is that I generate less power in the drops than on the hoods and after a while my cadence starts to suffer. That's why I know there is a real aero benefit since even when putting out less power my speed is either the same or faster.
If I could figure out how to maintain my power output in the drops then I would have something.