One discussion point I've not seen is how good the upmixer works on non-atmos content:
Once people invest $$$$ into new AVR and the speakers, you do want to use that gear.
That will be part of the make it or break it, who the heck is going to re-purchase good blu-rays just for atmos re-mix? Not I.
Will the studios even break their bank just to release a re-mix in atmos?
Maybe only for the biggie/legacy movies.
Now, if the atmos upmixer does a good job, then people can feel good about their purchase and not have buyers remorse/etc.
I've not read about any A vs B for the upmixer on non-atmos mix, why?
I'm running a full 11.2 set-up and can say that NeoX upmixer does add envelopment to my HT (prior was 7.1), enough that I leave it always on.
I've tried PLIIz and DSX, but NeoX seems to have the best balanced upmixer out there.