[rocqua]

The video cited above explicitly claims that the thinner wires (that last less long) are indeed more efficient. He backs it up with real experiments, and addresses the common claims that the Phoebus only did this to sell more products.

Specifically, the life-time of a bulb has to do with filament thickness (the filament sublimates until it is too thin, melts from resistance and breaks). At the same time, thinner fillaments will get hotter, and therefore be brighter at the same power level. (specifically, more of the heat energy is radiated away in the visible spectrum). This means bulb life-time and efficiency an inherent trade-off.