Good to hear that you like them.
I saw the B&O H9is at Best Buy for $414, and I decided to pick them up. I know I said they were uncomfortable, but I really wanted to give them a try since you can't accurately judge the sound of them through the Best Buy try out stations they have set up.
They look really, really nice. They feel nice too, and are far more comfortable than the PX. That's not to say that they're that comfortable though, since my ears would constantly touch the seams and the headphones wouldn't fully encompass my ears. They are lighter and softer though, which is a win in my book. The sliders are sturdy and are very smooth, which adds to the overall impression of these being a quality product. The only fault in the design in my opinion is the ear cups being too small, forcing some big-eared people to have their ears rub against the seams.
Both these and the PX have sensors which play or stop the music depending on whether you have them on or off. The H9i's didn't work well for me, and tend to take 3-4 seconds to pause when you take them off. This means that anyone around you will get a nice blast of the music you were listing to. Lifting one earcup doesn't work either - they have to be fully off your head for them to work. This, of course, may be just for me since everyone has a different size head. I let the sensors calibrate before putting the headphones on, so it's not a fault on my side. The sensors on the PX almost always worked and rarely messed up. They were quicker to play and stop music too, which I found odd since many reviewers said the opposite. The touch controls weren't all that bad, with the only thing that simply didn't work well being the volume controls. Transparency mode, enabling and disabling noise canceling, and pausing/playing all worked fine. I noticed that I'd sometimes accidentally pause or play the music by touching the earcup when taking the headphones off or putting them on, which wouldn't be a problem on the PXs button controls.
In terms of sound quality, I was very disappointed. I don't consider myself an audiophile at all - I just want my music to sound good. With that being said, everything I say about the sound is my opinion and shouldn't be taken critically. I just don't like how they sound.
The headphones have a very, very shrill and sharp sound on a lot of the highs. It was almost painful to listen to on volumes where I'd consider my PX perfect. They would distort on songs that had a lot of bass, something that my PXs never did. The volume itself is very unimpressive as well, but I'd say it's sufficient on most songs. While using noise canceling, these become extremely sibilant. Someone on the B&O forums pointed out that the song "Like Someone In Love" by Diana Krall has tons of distortion while ANC is on. I tried it out for myself, and it was just painful to listen to. On almost every "s" sound, I would actually wince. With noise canceling off, it's a lot better but still not great. I also noticed that the vocalists aren't as clear or up front as on the PXs. The instrumentals or even the bass of some songs seems like it masks the voice of the artist. I can't really put my finger on it though, but the sound and vocalists seem more masked and not as clear. There's a faint white noise when noise canceling is on too, something that the PXs usually didn't have. You can also hear another white noise when noise canceling is off and when music is playing, but it's nothing major and might just be me.
On the plus side, however, these didn't make the faint static noise for me when I changed the volume like on the PX. This seems to not happen for the majority though, so it doesn't really matter anyways.
In conclusion, these headphones are built very luxuriously but fall short with their features and sound. While their comfort exceeds the PX, they weren't entirely comfortable for me and the sound is not up to par.
Again, please don't take my mini review/comparison critically. It's just my personal opinion.
It looks like I'll be returning these for another pair of PXs. My real only issues with them were the faint static noise (but I'm willing to get past that and ignore it), and the fact that they don't accommodate as large of heads as the H9is.
They just barely fit me well on the largest setting.
But, compared to the plethora of issues that I encountered with the H9is, I'd say the the PXs are a much better choice.