I'm sure not every one measures the same, but when I had a Retul fit done, the guy demonstrated to me with power meter outputs that I generated more power in the hands on hoods, arms bent, appropriately angled back position. Riding in the drops (for me) is more aerodynamic, but at the cost of some power. Real world riding would seem to dictate some blend of alternating between the two, based on the situation and conditions. I have a pretty decent drop for an old man, more than a couple inches.