Nice comparison, Dave. I've used the xenon for nearly every outdoor outing I've been on for the last year and a half and have found it quite effective/versatile. The ability to dry out my base or shell layers beneath it has been its main asset over down. Cold/wet shouldn't happen often if you're layering/thermoregulating well, but when it does, its important to have a way to manage it. I know most people here poo-poo wearing puffies on the move, but I've found that if I'm cold and wet, I can dry out quite fast by moving quickly in this puffy. I take it off once I'm dry and feeling warm again. One trip I was especially glad to have the xenon:
I spent a long snowy day ice climbing in Rocky Mountain National Park last winter about 5 miles from the road. It snowed around 4-6 inches while we were out there, and my base/driclime was fairly wet by the end of the day. We made our way back primarily in the dark, bushwacking through thick sections of blowdown, with our tracks covered over and the temps hovering around single digits. I put the xenon over my base/driclime windshirt for most of the hike back. When we got back to the car I was amazed to discover that my base and dri-clime were bone dry with just a little bit of moisture still in the xenon. Had we lost our way on the return, I'm confident that my layers would have dried out enough that I could have thrown my belay jacket on top and been fine overnight. Since then, its provided me with some extra confidence and security in my layering system.
In winter, its a versatile enough to wear when belaying in mild temps (or restbreak), climbing or moving in frigid temps, or for transitions and descents bc skiing. For summer, it mainly gets used for stops/overnight, but its light and warm enough that I've never missed the WM flash i used to own. Speaking of which, I would add that the xenon feel significantly warmer than other light synthetics I've tried like the MB thermawrap parka. I'd attribute this partly to the primaloft 1, but mostly to the continuous insulation rather than stitch through. Its impressive that it feels about as warm as the pata down jacket, as I believe most synths in that weight class wouldn't. And finally, I'd agree that it has lost some insulation value over the time I've used it.
As to other options, I'm most definitely curious about water resistant down in the upcoming ghost whisperer and about polartec alpha garments. Seeing as I've torn this jacket about a 8 times, I don't think a down piece would be quite as functional for climbing/skiing (flying feathers), and the equivalent alpha pieces seem to be a bit heavier, I will likely stick to a xenon. Having powerstretch side vents and a more breathable shell material, like an arc atom lt, would make it even more versatile IMO.
Anyway, just thought I'd add my experience and pay tribute to a piece thats more than earned its place in my kit. Dave, hope to see you putting some of the newer insulations to the test going forward. (Sh**, I just used the phrase 'going forward'. Oh well.)