There are a couple of ideas that I would like to add to the discussion of lower port tunes. First, I don't believe that we hear most sounds in isolation. We hear deeper/louder bass tones in relation to mid-bass tones, and vice-versa. If the relative proportion of low-bass to mid-bass SPL changes, we may be able to hear a difference in the overall tonal quality of the sound. That is one reason why some people deliberately create low-bass house curves.
A subwoofer with a lower port tune almost certainly has a relatively higher proportion of low-bass to mid-bass, for reasons that were explained earlier. There is no free lunch! Lower-tuned subwoofers necessarily trade-away some mid-bass SPL in exchange for more low-bass SPL. That trade-off may be either a good thing or a bad thing, depending on the individual, and also on his listening habits (movies with strong LFE content, versus acoustic music, for instance), but to many it is a perceptible thing.
The second component to the reason that some people may hear differences in the tonal quality of low-tuned ported subs has to do with the way we hear low-frequencies. Below 30Hz, and increasingly below 25Hz, and then even more below 20Hz, we may be feeling low-frequency tactile sensations almost inextricably with the low-frequency sounds we are hearing. As frequencies go lower, it may become more-and-more difficult to separate what we hear from what we feel. That is particularly true with complex sounds, each consisting of both fundamentals, and harmonics of those fundamentals.
So, separating what we actually hear from what we feel below, let's say 25Hz and lower, can be very difficult. And, ported subs produce not only more SPL within about an octave of their port tune, they also produce relatively more particle velocity and corresponding tactile response (TR). All subwoofers produce particle velocity (literally the movement of air particles themselves, as opposed to the movement of bass frequencies through the air, which we define as SPL) due to the forward movement of the driver. More excursion equals more air movement and more TR.
Low-tuned ported subwoofers tend to have drivers with stronger excursion capabilities, and they also have ports which are moving more air at lower frequencies. That movement of air through the ports also contributes to increased particle velocity. And, that particle velocity is highest as the frequencies approach the port tune of a subwoofer. So, a low-tuned ported subwoofer is not only going to have proportionally more SPL at low-frequencies, than a higher tuned sub, it is also going to be producing proportionally more low-frequency TR than a higher tuned sub. And, as noted, below about 25Hz, and especially below 20Hz, most of us will have a lot of difficulty separating the hearing sensation from the feeling sensation. We will just perceive the combined sensation of having more low-bass.
I think that the above is a reasonable explanation for the differences that people experience with lower tuned subwoofers. Some people like that experience and some don't. Hop's father, for instance, didn't particularly like it, compared to a higher tuned subwoofer. But, the idea that subwoofers which go lower sound--well, lower--is a pretty logical one.
It's true with speakers too, as anyone who has ever upgraded to larger speakers, with deeper capabilities, already knows. The larger speakers, with a lower frequency response, have a relatively deeper tone, because the proportion of higher bass frequencies to lower bass frequencies has changed. And our ears can detect that change in proportion. So, I believe that what most people "hear" with lower tuned subwoofers is a change in the relative proportion of low-bass to mid-bass, combined with an increase in low-frequency TR.
The increased TR would mainly be perceptible with movies, or music with strong low-bass effects, because some increased excursion and port wind might be required to produce more noticeable low-bass TR. But, the slightly deeper tone might be perceived by some people, even at more normal bass volumes, and for more normal content. I think a lot of that would depend on how much people were boosting their subwoofers for whatever type of listening material we were considering.
FWIW, I think that there is a strong YMMV component to this whole issue of what we hear and feel, and what we like when we hear and feel whatever it is we do. I don't think that our perceptions are identical, and I don't think that our preferences regarding those perceptions are identical either.
GUIDE TO SUBWOOFER CALIBRATION AND BASS PREFERENCES
* The Guide linked above is a comprehensive guide to Audio & HT systems, including:
Speaker placements & Room treatments; HT calibration & Room EQ; Room gain; Bass
Preferences; Subwoofer Buyer's Guide: Sealed/ported; ID subs; Subwoofer placement.