Frank, I don't think that there are too many rooms that can allow front Width speakers, like normal rooms in real people's homes.
Audyssey DSX is for the hardcore surround addicts. ...Similar to Yamaha four Presence speakers (front & rear).
Because, with each music recording, and with each movie soundtrack, even within each track or chapter, the sound coming from them varies constantly. With Yamaha DSP you can hear that effect easily, and you have to switch audio mode or adjust the parameters.
...And I don't know if you know but those high-end Yamaha receivers have tons of those EQ parameters. ...And several music and movie modes, all in DSP power of course.
For certain type of music on CD, when recorded @ different studios for different tracks, it is a constant moving target; forget it.
For well recorded Jazz music (ECM record label), it can add more presence indeed, but with restraint.
Audyssey DSX, the front Width and Height channels; one movie not too bad the next movie awful.
For music the same. ...So here too you are with your remote control in hand, don't put it on the table or you risk to miss what the music recording/mixing engineer, or what the movie director in collaboration with the sound/music engineer wanted you to hear.
You have roughly a 95% chance of being addicted to your own sound mixing, and not the one from the maestro.
...And no matter how well Yamaha implemented his Trifield or Quadfield DSP in their products. ...Like I said, it is a constant moving target that requires constant manual calibration.
And no matter how well Audyssey DSX algorithms work. ...Because it simply doesn't always, and no matter how meticulously you position your front Width and Height speakers with all the room treatments more or less acoustically corrected and calibrated and equalized..
Yes, it's a sound addiction, like a drug, and you can easily overdose from it without even noticing.
Anyway, that's my take and I highly respect people who extensively love to experiment with drugs (sounds).
Now there is a new sheriff in town, a new conductor: