Welcome asb! Sorry for late reply but I just saw your post today.
Your comments regarding installation of Bionor's aren't entirely correct. As far as coherence goes I agree that the more distance from the speaker the better, 13m-15m is ideal but I have no problems even at 5m in my room and seating is currently at 9m from front of baffle and sound is fully integrated. Yes for stereo audiophile style imaging there's a sweet spot but the way the room is energized you can sit or walk around almost anywhere in the room and the sound quality will remain exactly the same as will the level and energy very much like walking around a live venue. Horns might be directional but the Bionors were made for a 700 seat theater so they also have a wide dispersion pattern.
Many people have visited me and no one found integration an issue even at closer distances in my place. I don't know what you've heard for yourself but electronics and setup play a major role in proper integration of any speaker including the Bionors, specially within listening room boundaries. I'm aware of Andreas's installation with the metal horns hung inversely on the inside of woofer horn section but he's also using the lenses on his. I haven't tried them in a large space but I didn't like the lenses in my listening room. The speakers seem slightly more articulate with the lenses on but they beam the sound instead of the wider, unforced large dispersed sound of the horn without them, the lenses are also very directional in a small space I really don't like them nor do any of my clients with Eurodyns or speakers I've made using the same Siemens horns. It's a matter of preference using the lens and hanging the horn upside down changes the balance too much for my taste and you need to start compensating for what's lost.
I've done my experiments making different sized baffles or copying the original and in every case the new wood changed the tonality of the speaker, generally duller, the original wood is part of the sound and one can't mess with it for aesthetics. Contrary to what you think the baffle dimensions are more than bass extension, Bionor is a 4 way speaker you have the two way electronic crossover and 2 ways mechanical being the metal horn and the wood horn with baffle. Speaker height is very much part of the design dropping the speakers to the floor alters the sound balance same as messing with the crossover. Sticking them in the corners or up against the wall has the same affect on the Bionors as any other speaker, boomy & muddy! I've seen pictures of the Russian pair on the floor close to the back of the room and toe'd in and heard various Eurodyns in small short baffles, they don't work properly! Some people are forced to make compromises but in many cases they don't know any better when building their baffles, there's a reason why Siemens engineers spec's them the way they did! The other thing you need to consider is the age of these speakers after all these years they don't all perform at the same level, there are better and worse examples the only way to get it right is having experience with many pairs and knowing how they should sound.
Threads do sometime meander and change course on WBF, just the way things are...
.david
