Is the most efficient speaker the best speaker?

Atmasphere is absolutely right. Horns rule. Lower power requirements equals more headroom and better dynamics.
Put your dollars into amplifier refinement rather than raw power. Quality over quantity.

Even speakers with efficiency an of 100 dB/W in a typical setting, will require about 200 Watts per channel to achieve 120 dB. One would have to have an extremely large room to adequately contain 120 dB with any semblance of scale, and require much more power in such a room than the 200 Watts per channel suggested above. Such power levels from tubes come at quite an initial cost, continuing costs, and some inherent technological considerations. Most people have neither the space, disposable income or even feel the need for such a luxury. Please don't get me started on the consequences of having to listen to horns in the first place.

And, they're off and running. . . Again.

Is it really necessary to achieve potentially hearing damaging levels of 100db and higher to fully enjoy one`s home audio system? I don`t believe people have to mimic ultra high and uncomfortable sound pressure if they have a reasonably quality system with very good musicality and resolution(and want good hearing a few years down the road).

Charles1dad, with all due respect to Atmasphere, I'm confident that he was only referring to intermittent peak levels. On the one hand, I do agree with him that being able to replicate absolute live levels is a good thing, on the other hand, I agree with you, in the big scheme of things it doesn't seem like the highest priority for most of us.