Horn based loudspeakers why the controversy?

I've heard dozens of horn systems.  Of the complete systems, I like: the Edgarhorn systems I've heard; some of the Volti systems I've heard were okay, but not that great for my taste; Klipschorn and Lascala not my favorites; Altec Voice of the Theater not my favorites; Goto-good, but big and expensive); and a few more that I can't remember who built them. 

Back-loaded horn systems include: Beauhorn, Rethm, Charney, and a few others.

Mostly, I've heard custom systems built around Western Electric, International Projector Company, Yoshimura Laboratories, and Jensen --drivers and horns.  I've heard systems that use new drivers from G.I.P (Japan) that are replicas of old Western Electric drivers that sound terrific (they ought to, given the prices of these drivers).

My own system is built around a horn-based system from Strumenti Acustici de Precisione (twin 12" Alnico magnet woofers in an Onken cabinet, compression driver and horn midrange (I swapped out what came with the system and replaced the midrange with a Western Electric 713b driver and a 12025 sectoral horn), and a bullet tweeter.  

... If mid bass and bass are proper horns they yield some of the best mid bass and bass availble but as I mentioned above its were product gets compromised DIY types are free to build proper sized but they are not easily availble maybe this is part of the issue hardly anyone has heard or owned full range all horn loaded systems and they take knowledge and sometimes real physical work to set up. And face it most just want to easily buy just open box and plug in. But with many things in life sometimes whats easy and convenient is not whats best.

The size of an all-horn system that extends down 20-30Hz range, or even lower, is not trivial, certainly not with dual subs or more. DIY is usually the approach to seek here as there are relatively few pre-assembled solutions to be had, and the ones that are typically counts pro subs tuned higher (around 35-45Hz, perhaps) for more pronounced midbass impact. Danley Sound Labs on the other hand, a pro reinforcement manufacturer, offer viable horn sub alternatives for domestic use, some of which extends down 20Hz and lower. The very few "hifi" options there are of horn subs are really outrageously priced and mostly statement products (what’s expensive here tends to simply be luxury finish, added to more complex product assembly), and this narrows down the appeal to the über-wealthy that are hardly representative of audiophiles in general. So, DIY or used Vintage is the route to go (if not Danley), and this often requires some elaborate research to get a bearing on the iterations that suit one’s needs and possible practical limitations the best. It’s an interesting journey, however, and there are DIY-communities around (like Avsforum, Bill Fitz Maurice forum, Klipsch ditto and others) that are very helpful to aid one’s quest here.

My own tapped horn subs extends to 20Hz, and it’s a different bass compared to the direct radiator subs I’ve heard - indeed, I’ve never heard bass of this quality before. Horn bass like this doesn’t have what I regard as a degree of thickening, smear and slightly massive feel of some if not most DR subs, and the sheer presence, smoothness, ease and informative nature of TH(/FLH) subs is rather unique. Horn bass somehow sounds less like "bass" and more like an enveloping, differentiated downwards extension (with a livelier upper band as well), and it can give the initial impression that some of the more heavy-handed or even ponderous weight and "pulsating" nature of DR’s is a disadvantage with movies in particular. You quickly realize though, or so I find, that the differentiation of horn bass opens it up with better dynamics to boot, and it makes for a more whole, coherent overall experience.

You might think that boxes this big (in my case 20 cubic feet per horn) would overwhelm the experience (and of course you could make them if dialed too hot) as a sonic bass entity per se, but quite to the contrary they blend in more effectively; they’re simply easier to integrate with all-horn mains, I find, with the proviso that the size of the horns themselves can be a challenge to make acoustically invisible in one’s listening room, unless space is sufficient of even abundant.

In any case I’m still baffled to see "horn" speaker manufacturers mostly resort to DR subs to augment the horns in the frequency range above, seeing how it usually diminishes the coherency, sheer quality and dynamics of the sound. As horn proponents I'd urge to let size be size, and physics have their say; are we audiophiles or not? :)

I sold a good num of very large front and back loaded sub bass systems for home audio and also for simulator use. The costs get crazy high very fast. Audiophiles also want veneer or other deluxe finish this adds greatly to costs when things get crazy large, it also adds greatly to packing costs and shipping since you have to pack to keep a 800lb full veneered horn from even the slightest damage a imposible task. With home installs many times you have to hire someone to help tote and someone who knows set up (I had to hire 6 men to move my subbass horn to new audioroom). And most audiorooms can not house or even if they could horn wouldnt fit up stairs through door arround corner etc. I did put alot of design effort into more portable giant designs and ones that easily come apart to fit such but markets limited and the above is problematic. Today I turn customers away and just build the large ones for my own use. Its far easier and cheaper to just slap ported cab to cover mid and bass thus why most are such.

@larryi - thank you, you've certainly heard many horn systems!
Not heard of the Italian  make you have  Strumenti Acustici de Precisione, as I have an Italy backgroung , I will make sure I try and find a dealer in italy close to me to have a listen when I visit. I also would like to hear a pair of Ocello's from the UK. I have heard some big horns at various Hi-Fi shows, 'Classic Audio Loudspeakers' Horns springs to mind from memory. My Oris 150's were made by johnK, I've had them since 2007, and I must say that I would not swap them for any of the Horns that I have heard so far. They are streets ahead of my stock Klipschorns sound wise.

Except music with a 5 string bass at 31hz for the low B, percussion overtones, pianos, the ambient sound around live orchestras, life...etc....

Well. life is not music, but yes, there are a fair number of sources for below 40Hz bass. Still, a lot of popular music is excluded. Being that reviewers often listen to classical, pipe organ, and such as references, it's perplexing as to why so many confuse the 2nd octave for the first. I realize speakers often get some reinforcement in way of room placement, but still, many "budget" floorstanders don't produce anything useful below 35Hz. I'd rather have a speaker that sacrifices everything below 40Hz in exchange for tactile and defined bass above that - which is what you get with Klispch Heritage.