I consider myself a neutral observer in this matter. One of my best friends has K-horns, though I don't. It's been a long time since I needed their capacity for "loud", my house isn't a good fit for them, and, mainly, I happen to prefer other traits in speakers. However, for those who want the strong points of a horn and don't mind their drawbacks, they are a great choice.
mlsstl --
One of the misconceptions of horns seems to be focusing more exclusively on their abilities into high SPL's - perhaps your comparison to "muscle cars" above meant to say the same thing? Indeed muscle cars combined with poor suspensions and brakes makes them appear even more brute and simple, like big muscles and little to no brains and more like a Camarro than a Porsche 911 or some Ferrari (perhaps a poor example). Maybe I'm reading too much into your replies, but any claim of neutrality combined with remarks as these is kind of like having your cake and eat it too. Like saying "to each their own, but from an objective standpoint horns are something [loud] like this [and mostly that]." We're mainly talking the K-horns here, and they seem to be your primary focus, but selling them short on loudness is hardly the whole story. To my ears horns more often than not actually excel at lower volumes (and higher as well), coupled with a capacity to emulate the sound of live acoustic music - of which dynamics and effortless reproduction at higher volumes is very much part of. And yes, some of them are rather "colorful," but it goes without saying that non-horn speakers "retract" something from the audible experience in ways that turns it into "coloration" as well.