As others have already said, low efficiency does not translate to lack of dynamic range.
Dynamic range in lower efficiency speaker, given high power, high current amps, can, and does equal the dynamic range of high efficiency speakers.
And for me, that 'liveness' that people talk about with high efficiency speakers (although I don't concede that this is an attribute of high efficiency), comes at the expense of too many other attributes, for me to make the trade off.
I've heard plenty of high efficiency speakers: Klipsch Forte, Heresy IV, La Scalla, etc., JBL L82, Zu, and others, and all the ones I've heard, trade off their efficiency for (IMO) less than optimum timbral accuracy, lack of a focused and layered soundstage, greater frequency response aberrations. And most of them, to me, seem to create a veneer of sounding like a PA system, that overlays everything.
Unless one gets into the higher echelon of high efficiency speaker; Cessaro, Acapella, AvantGarde Acoustics, etc, at which point, there seems to be no real tradeoffs between high efficiency, and most of those other attribute missing from most of the other high efficiency speakers, at lower price ranges.