The thing several people in that thread, and many people miss, is the difference between input and output. Eurochris is right. There is no "free power," energy is conserved, so the same power has to come from the battery no matter how it is applied on the output side of the regulator. The voltage of the battery does not change, so if you were to see a difference in amp draw on the battery with different coils, you would see a different wattage into the regulator, which would either be output as a higher wattage or wasted as heat.
Efficiency differences are related to regulator efficiency at different voltages, and atomizer efficiency with different coil/wick arrangements.