Indeed, the most fascinating subject! Great posts above.
My experience with the approaches is that I can second the observation that we need driver diameter and baffle width to achieve effortless and full midbass. Skinny fronts and smaller, very high excursion woofers (practically woofy tweeters) can deliver the quantity but cannot deliver the quality, the dynamic range, nor the harmonic integrity. Just think of the audiophile proverb as delivered to a flaming rose bush from the mouth of Harry Pearson the high end audio God : "if you can see the cone moving it's not high fidelity anymore". The facts of physics do not change, his observation is as valid today as it was 30 years ago.
For woofers, it's not the ability to move a foot, or two gallons of air - it's the ability to couple the energy to the air that counts. That was and still is the prime requisite for high quality bass response.
People do not realize that out of the several inches of cone excursion only a fraction of the pushed air is going to participate in the formation of sound waves of the desired frequency - those obscenely flapping small pistons operate with 99% energy loss, or worse!
I do concur with the posts above, most audiophiles never experienced high quality bass. When it happens, you feel as if you are lifted in the air, your room and your skin feels energized, you feel the scale... similar experiences as experiencing a live concert. And it needs not be earsplitting volume to feel that way. Can dial volume down, and the feeling stays.
As far as bass response goes, most people experience it down to 40Hz-ish regions. When the system delivers down to 30Hz, that brings a giant transformation in experiencing it. (Weight,,energy, exhilaration.)
Another very big leap when it can reach 25Hz with authority. That's a profound transformation, grounding the instruments in reality. The image becomes much more solid, real. Yes - even a flute, and the singers!
Next jump is when you get to 20Hz. Now you feel the space is opening up, and the music fills the entire room. Not just the bass - the violins, etc, the sound becomes palpable.
And another jump when you can get down to below 20Hz. I'm at this stage now, system good to go to 13Hz, and has content down to 11.0Hz. -- and that at 102dB/Wm. Here, the ability to provide subsonics is the elusive nectar. You also need room to house the frequencies - by room can support a 13Hz wave, so happy marriage there. This gives the experience to feel as if you are at the concert hall for real. Concert halls have sub 20Hz waves due to the hall size, and our ears and bodies pick that up as the cue for the enormous space. These waves are felt by the body primarily, not the ear! The frequencies below 20Hz affect the endocrine system, so music with electronic programmed subsonic content does act like a transcendental experience, as it directly alters your hormonal balance, changing how you feel in your body and how you experience reality. I found this effect far more addictive than any chemical addiction (alcohol and substances), so it's a blessing in disguise that most people do not have access to this frequency range.
Also, our bodies are not built to sustain regular exposure to subsonics... while normal music does not put you in such danger, but programmed electronic music (that has high infrasound content) certainly does.
To stay on the safe side: have your system go down to 18Hz. That will give you the most amazing transformative experience already, without fear of bursting the spleen... ;