Just wanted to report back from my six months of ownership.
I have owned all of the B&W headphones to date except for the original P5s1.
I have tried or owned a handful of Focal headphones including Bathys.
I also own a pair of open headphones that cost three times as much as PX8. (Hifiman Arya)
I listen mainly sitting at my desk (home) when working, or walking around the house doing chores, or when travelling (air/train).
Even when at my desk, I find myself reaching for PX8 more often than Bathys or Arya. Arya is a great and technically superior headphone, but it just doesnt offer the same ease of listening, the same warm signature and the comfort of PX8. Also there is the cable. And the fact that PX8 allwos me to multipoint to both an iDevice and my computer, and take calls without taking them off.
I have now sold my Bathys. They are good but just didnt get any listening time here. I took them on a trip and was disappointed with them as a travel companion. PX8 is smaller, better ANC and overall just more versatile.
Will sell my old Sony XM3.
And probably sell my Aryas...
All in all, I am super happy with the performance of the PX8. Real home run.