We have two models with different upper bass horns, one is indeed a 140hz horn (77 cm diameter) and the original, bigger horn at 110 hz (92 cm diameter) Both tactrix both made from the same materials (MDF) and finished in the same automotive finish.
The difference in sound is substantial, but also de difference in size, though it doesnt seem like much, once you check out the diameter and see them side by side you can see how different they are. The 140 hz horn can play in a hotel room and still have an acceptable sound, the 110 hz is too big for that. The minimal room size for a 140 hz horn I would say is between 13-14 ft X 20 ft, The 110 hz at least 18 ft on the smaller side, though Romy made some magic in his small apartment system in downtown Boston.
With a Fane Studio 8M driver on both, the measured sound differences are not huge, the 140 hz coupled to the floor will go down, room dependant, to around 115 hz, while the 110hz coupled to the floor will go down to under 100hz, again measured response.
The sound of the 140 hz horn is more open on top with a very natural midrange, it will blend very easily with almost any driver on top, imagine it as the best high end system you have ever heard, but still a playback.
The sound of the 110 hz horn is closer to a live presentation, it is more dynamic, the response of the horn seems signifcantly lower to the point where it becomes very listenable even without a channel under it making the bass. It relies more on the following driver to make a perfect midrange and integration takes more care, it seems effortless on the bass and more forgiving to the bass channel, since it is already doing most of the hard work.
A final system with the 110 hz horn will sound better, more lively and effortless, the system with the 140 hz is still fantastic and still alive but size does matter, and where you will really notice the differences will be when you play a big orchestra and get better definition of instruments in that range.
Both systems can play with the same bass modules we designed based on a tapped horn with response optimized for 110 hz horn, playing almost flat down to 25 hz. They blend in very well with both front horns, but the bigger dynamic response of the bigger upper bass horn is still noticeable. Maybe if we redesign the bass modules optimized for the 140 hz horn the differences will become smaller, but I am not be too confident this will happen, so much I have not gone forward with such redesign.
(PS: keep in mind The throat on the 140 hz horn is 5" and the one on the 110 hz horn is 4")