Just a "quick" note as it is 3:30am and I really should be in bed.
I've never heard anyone say that the overhead speakers in Atmos are the only ones that really are important for Atmos.
Again, my suggestions are to hit the "best optimal target" from there compromises have to be made for just about every room. Some people ARE using QS speakers for the bed layer (not overhead) speakers and having what I would call an "improved experience" with Atmos vs. without the overheads, but it is still a compromise in what Atmos is capable of.
Think of it this way. You have lasers instead of sound waves coming out of monopole speakers and you can get very accurate placement of sounds within a 3D space with lasers. Now replace 2 (or 4 depending on how many QS speakers) of those single directional lasers with 4 lasers each pointing into 4 different directions each. You can somewhat pinpoint some sounds, but you are also spraying into 2 or 3 other undesirable directions. It just messes with the 3D placement. Not impossible, because you still have other correctly oriented lasers helping to drive the location in the room, but the "noise" from the "QS spray pattern" that is so great with traditional surround sound is messing up the accuracy of what Atmos is trying to do.
Again, it is a compromise, and yes people are doing it and really liking it, but it isn't that they are liking the QS speakers in an Atmos setup, they are liking the addition of 2 or 4 precise overhead speakers being added to fill in more of the soundscape in their room. Little do they know that they are not hitting all of the potential.
Also, the idea of putting a QS speaker between the 1st and 2nd row of seats on the left and right side was something that I toyed with too. It seemed like a great way to have a single speaker play back side surround information to both rows, however you are still spraying sound up and down in that scenario which again isn't ideal. Since Axiom doesn't make bipole speakers (the only type that really would fit that scenario) and the quadpole is spraying everywhere, monopole is still the ideal path.
But again, compromises are made every day and people can still have an enjoyable experience.
