A general question here. How many have tried to listen to a good speaker system where the front wall behind the speakers is treated with broad-band damping down to around 100 Hz and compared that to a ”live wall” and used EQ to adjust the effect of the room? Or for that matter in-wall speakers with traditional speakers? Perhaps forgotten now but e.g. the Carlsson/Sonab speakers worked together with the front wall to make it more invisible and I think the Allison speakers had similar ideas. With todays shallow horns or waveguides at least the tweeters are of less problems but you still have effects of the mid and woofers where you have boundary effects from the front wall. Whereas a good dispersion laterally fix the side walls you always have a front wall reflection that never has the same pattern as the side walls.
A second point is the level and delay of the side wall reflections. I am not sure you can extrapolate studies where the room is rather laege like the Harman test room with a much smaller room. If you want delays > 10-15 ms compared to the direct sound you would need a large room. Another solution is to have narrow dispersion or heavy toe-in so that reflections are coming more from the later reflections of the opposite side-wall.
A second point is the level and delay of the side wall reflections. I am not sure you can extrapolate studies where the room is rather laege like the Harman test room with a much smaller room. If you want delays > 10-15 ms compared to the direct sound you would need a large room. Another solution is to have narrow dispersion or heavy toe-in so that reflections are coming more from the later reflections of the opposite side-wall.