Rating: 5 / 5
The Rab Xenon (Spring '11) is a lightweight, well-featured synthetic insulation puffy jacket - my men's medium comes in at just under 10.4oz (294.3g - this is unmodified weight less retail tags - I'll reweigh the jacket after removing laundry tags, hood retention clip) - that's lighter than my patagonia nano-puff pullover. Full disclosure, my nano-puff is a men's large (vs. medium - I shrunk a bit), but still - at 10.9oz/309g the nano is heavier by half an ounce and missing many of the features of the Xenon - the Patagonia has no hood, no hand-warmer pockets and isn't full-zip.
Materials/Construction: The Pertex Quantum GL 10D fabric used in the jacket's construction is the real deal - very lightweight, but has held up extremely well (no visible wear to date) after about a week-plus in the backcountry and a fall season's worth of around town wear. Construction quality is good if not great, in particular I find the stitching to be a step above - tight, clean and even throughout.
Fit: Trim, fairly athletic, but has room for a small gut should you be rocking one. For reference, I am 5'8", 165lbs (and falling), and find the medium to be a very satisfying fit. There's room enough to layer a few mid-weight baselayer tops under the jacket, but adding a down vest or similar high-volume item to the mix would likely start to compress the insulation. The jacket does well as a midlayer, and is adequately breathable.
Warmth: With a t-shirt (Icebreaker 200g/m2 Hopper T) the garment was warm in camp (zero output, no fire, moderate wind) for me down to 35F. Lower than that and I was happy to add a L/S 200g/m2 weight top and cap.
A few other notes - The hand-warmer pockets are not zippered, they are open. And although their presence runs against my minimalist nature, they've been super-convenient on late-night walks around town and in camp (Windy and cold? No gloves/thin fleece gloves that are worthless against wind? No problem). The Juicy color is bright, redder than orange IMO - not for everyone but I like it, and will be great should I ever need a beacon for SAR. Jacket cuts wind very, very well. Also makes a decent pillow - assuming you don't need to don it for additional warmth, just stuff it into the zippered pocket and bam - you've got pillow. When stuffed into its pocket you can see just how thin the Quantum GL fabric is - you can see right through it. Hood - looks slightly goofy in use, but performs where it matters - vision is fine, moves well, keeps out wind.
As a minimalist, I would love to see what kind of weight savings Rab could achieve by ditching the hand warmer pockets, hood retention clip (yes, there is a small bit of webbing/buckle to keep the hood from what? Blowing around when you're not wearing it in 60mph wind? Save me a few grams) and going with a pullover design. With these changes I think Rab would be flirting with 9oz, which would be truly impressive for a hooded synthetic puffy - if you're reading this, Rab, make it happen.
Sure, you can get lighter and warmer by going with down, but down is next to worthless when it gets wet. That's the main advantage of synthetics - when wet, Primaloft One is at or close to the top of the heap for best performing insulation. So, when the forecast is wet, questionable, or the trip is just too long to know what you will encounter, I don't really think you can do much better than this jacket for 3-season UL backpacking. Other than perhaps the BPL Cocoon Hoody (which is sadly no longer available).