Given that almost all non-coaxial speakers have pretty nasty cancellations around the crossover(s), it stands to reason that fairly heavy absorption hanging from the ceiling to heavily reduce the ceiling ER is much more important than any side wall or rear wall treatment, regardless of horizontal directivity behavior. Even with coaxial designs, I'd consider it quite important.
It is immediately audible hanging a cloud in a room that has a reflective ceiling - everything gets "tighter" and the soundstage becomes much clearer and less fuzzy.
It is immediately audible hanging a cloud in a room that has a reflective ceiling - everything gets "tighter" and the soundstage becomes much clearer and less fuzzy.