Just as a thoughtful aside, more purpose and dedication goes into the matrixing process than some engineers put into the actual recording.
Personally, I find it amazing that Roger Dressler, Jim Fosgate and others have the genius to take something and make it more life like and real, whether from two channel, four channel, or five channel sources. This has been a long, evolutionary process that didn't always work convincingly. It's convincing now, and it just keeps getting better.
I still love two channel sound. My most expensive gear is two-channel, and it sounds spectacular, but my less expensive (though not cheap) surround systems sound more real in the long run, even when running PLIIx from stereo.
Honestly, I do not care what's discrete and what's matrixed. I care about how it sounds in the room and where it takes me outside the room. PLIIx does a smash up job, especially after two skilled guys stop over and tweak it. (Thanks guys, you know who you are.) PLIIx is excellent, and I've already bought two spare speakers for a couple of my systems in anticipation of the full PLIIz rollout.
So Roger, if you read this, thanks for the work and well done.
What I can afford, when I can afford it...