In my opinion, a bipolar's side-null is beneficial in a multichannel setup.
The reverberant energy is a separate event from the first-arrival energy (produced by the front channels), and different priorities come into play.
You do not want the rear channels to stand out as distinct sources; rather, you want them contributing to the ambience and sense of spaciousness, and perhaps the occasional off-screen sound effect. By aiming the null towards the listening area, a bipole can contribute more beneficial ambient energy, relatively speaking, without calling attention to itself as a separate and distinct sound source.
Duke
dealer/manufacturer (nope, I neither build nor sell dipole surround speakers at this time)
The reverberant energy is a separate event from the first-arrival energy (produced by the front channels), and different priorities come into play.
You do not want the rear channels to stand out as distinct sources; rather, you want them contributing to the ambience and sense of spaciousness, and perhaps the occasional off-screen sound effect. By aiming the null towards the listening area, a bipole can contribute more beneficial ambient energy, relatively speaking, without calling attention to itself as a separate and distinct sound source.
Duke
dealer/manufacturer (nope, I neither build nor sell dipole surround speakers at this time)