Alrighty, folks! The ultimate horn skeptic has sat down and listened to a fully horn loaded system in the form of Klipsch LaScala II.
I'll start with the cons and finish with the pros.
The imaging wasn't up to the standard of my Focal. I'm willing to chalk some of that up to the room, though I feel that the room was about as dead as my room at home. Specifically, the soundstage was strictly limited to the space between the speakers. The sound was more forward, but certainly not attacking my face or anything. The bass was AWOL at 40Hz; a fact I couldn't live with.
The soundstage between the speakers was very good. I relent from using "excellent" only because the scale of depth didn't beat my Focal. The dynamics were first class, definitely besting my Focal, but not by a wide margin. The bass was great before it went on vacation.
In conclusion, I'd have to do a lot more listening before I decided if such physical dynamics are something I'd want to live with. I can imagine them being fatiguing, especially with certain albums I like, but I can appreciate the thrill of such an aggressive character. The lack of bass is a total non-starter though.
I liked them. I would sit and listen to them for hours to better understand them and how I heard them. But at their price point, $8,000, I feel like I'm get 90-95% of the dynamics, better soundstage, and more deep bass for half the price in my Focal. I can conceive of better placement and room treatment tipping the balance, but I didn't hear that.
So there. Nobody can call me dishonest. I think most would call LaScala II great examples of a fully horn loaded system. I listened. I liked them a lot. Probably not speakers I'd buy though.