With the right AVR, I would almost consider a 5.x.6 setup. But I used to enjoy video games quite a bit, and the Rears in many of my favorite games were used to great effect. Another interesting tidbit is that some DTS5.1 audio discs I have are coded to use a Rear Center, not the normal Front Center. The processing sends the Rear Center signal to the Stereo Rears instead.
As to a 5-channel bed layer, most material is seemingly made for that configuration. Several people have stated that the rears just don’t do enough to justify them.
Who is correct?
Personally, I’ve considered experimenting with a single Rear Center to see if I could do 6 channels of Atmos. My current rears are wall-mounted at about 7’ due to a closet on one side of the room. I could see myself then setting up Atmos using Front Height, Top Middle, and Rear Height.
Why? Because that seems like it might maximize my room better. It’s small, 11x15’, ~2000’3 with a sloped clerestory ceiling.
The point being there is no right or wrong. I think most important is knowing and understanding Dolby’s recommendations well enough to be able to adapt them to any room. As it is, that is the key that gets overlooked all to frequently, IMO! The most successful rigs are the ones in a room which is considered as a part of the system itself, and it very much is.