Yes, Atmos is a new beast. I think I understand your comment about absolute reviews and people having different/diverse setups but that has always been the case.I am thinking that with Atmos mixes it is difficult to make absolute reviews. We will see people saying that you need a 11.4.8 setup to really appreciate Abbey Road.
I researched Atmos configurations and systems quite a bit before purchasing my new equipment. I decided that a 4 speaker height setup would truly be the minimum I would want so that the sounds could be mixed into a 3D space around/above me vs a 2 ceiling speaker setup. Ideally, the ceiling speakers are spaced an equal distance in front and behind you. You are in the center of the height speakers. The height speakers along with the floor speakers will allow sounds to be placed anywhere around you in a 3D space. I also decided that I wanted a higher quality speaker vs a lower quality speaker for heights since I wanted to listen to Atmos music vs just movie sound effects, leaves, rain, etc. I believe a 5.1.4 Atmos system would be the minimum setup to take full advantage of the new mixes.
Since I've updated my system, I have been paying more attention to my speakers than I have in while. So far I have found that I still prefer 5.1 sources played back to just my 5.2 speakers. My main quad speakers (Klipsch RF-7ii) are fairly tall and the sound does surround me and is above me as well. I've had to repeatedly verify that I'm not up-mixing to the height and rear speakers. However, music that has been mixed to Atmos (REM, Kraftwerk, INXS, etc) does sound wonderful with a definite taller expanded sound field around me. I believe a listener with the minimum 5.1.4 configuration will be able to hear the difference and make a valid review. We'll get to find out tomorrow!