When I built my last Home Theater, I had the opportunity to completely renovate the living room and first place the speakers at the locations recommended by the manufacturers (the best I could).
I implemented different speakers for Auro-3D than for Atmos, with speaker switches to select for each format. At that time, my Denon AVR did not have the compatibility between Auro and Atmos to use the Top speakers. Now it is possible since a firmware update.
For Atmos, I have the 4 Tops ‘in-ceiling’, at 45º elevation (approx.), with the tweeter orientable to the listening position.
For Auro-3D I hung bookshelf speakers from the ceiling, the same model as for the surrounds. Located just above the Fronts and Surrounds, as Auro-3D says, and oriented to “my head” when standing. That is, as said in a previous post, a little higher than to the sitting listening position.
My experience in this regard is that, although with the Atmos Tops (in-ceiling), I can decode Auro-3D and it doesn't sound bad at all, I like it better with the canonical Auro-3D configuration than with the Atmos Tops speakers.
In addition to the different location, I think the better quality of the Auro-3D hanging bookshelf speakers must have more influence than the built-in in-ceiling speakers, which, although not bad, are somewhat inferior.
Therefore, although I cannot recommend twice as many speakers, with speaker switches, which may not be within the reach of many installations, I can recommend that the Heights or Tops speakers be of significant quality, in principle the same as the rest speakers. As I use to say, they are not just “Effects Speakers” but rather they have to be capable of reproducing the same quantity and quality of music as the floor speakers.
