ATC's might deliver some of the coherency you like in the SL and still give you the dynamics and loudness that box speakers are known for. (Driver integration is better with active designs) I don't think you necessarily have to go away from box speakers to find what you are looking for.
The ambience from rear radiating devices is nice sounding, but it has very little to do with the original recording as you are not hearing the ambience of the venue but more reflections from your room; it will sometimes sound nice (when the recording has been made in an acoustically dead environment like most pop music) but may add confusion to what you hear on live music, jazz and orchestral works. Speakers with ambience are also much harder to setup unless they have an adjustment to control the a mount of rear radiation.
(Rear radiation causes cancellations in the forward radiating sound: a comb filter which your brain identifies as "ambience"....sound engineers use this trick to make a stereo sound from mono recordings by passing it through a comb filter...it gives an impression of a difuse large soundstage but may detract from the image)
The ambience from rear radiating devices is nice sounding, but it has very little to do with the original recording as you are not hearing the ambience of the venue but more reflections from your room; it will sometimes sound nice (when the recording has been made in an acoustically dead environment like most pop music) but may add confusion to what you hear on live music, jazz and orchestral works. Speakers with ambience are also much harder to setup unless they have an adjustment to control the a mount of rear radiation.
(Rear radiation causes cancellations in the forward radiating sound: a comb filter which your brain identifies as "ambience"....sound engineers use this trick to make a stereo sound from mono recordings by passing it through a comb filter...it gives an impression of a difuse large soundstage but may detract from the image)