I agree to a large degree, this is certainly true of own implementation - they get down to about 35Hz.. just:
The graph is both sides driven measured from my listening seat. From a subjective perspective they can do a bottom E fairly convincingly but drop very rapidly indeed below there. I've tried running sine waves from 20Hz in 1Hz increments and I can only start to hear some fundamental above 35Hz.
The speakers are in a rigid sealed (to a degree at least) box of about 75L. I understand that say Autographs can get the same driver down a lot further, but obviously we are talking something absolutely huge and remarkably expensive here.
I agree completely. It's all about shifting air without any strain or effort, and IMO that takes a big driver. The only thing I'd argue is I'd like some real energy down to 35-40Hz or so, a bass / bass guitar guitar bottom E is 41.5Hz, and to my mind the music suffers if a speaker is only capable of delivering harmonics there (e.g. my Klipsch Heresys which are out of the game at about 50-55Hz). It's easy to argue there is a lot below 40Hz too, a kick drum effectively rises rapidly from a 0Hz thwack, as indeed does a nice big bass amp etc, i.e. you pluck / hit the string and there is a hefty subsonic thud as the speaker reacts that constitutes much of the leading edge of the note, the sound of the string and speaker rapidly accelerating to pitch, think big Ampeg horn cab. I'd file that as nice to have out of a home stereo rather than essential, but the bottom E is part of the music, we needs that!
Tony.