Worthy 6,000 meter jacket - Rab Positron Jacket - Men's

I already own the Rab Neutrino Plus, from which this jacket supposedly is a refinement. I used the Neutrino Plus as a belay/summit jacket on a recent trip to Bolivia with great success. I was never cold in it, and we had some very cold summits. The Positron shares the same fill weight, but really is in its own class. It is lighter by 4 ounces (on my digital scales at home), uses water resistant down, has a much trimmer cut, and uses a mix of box wall and sewn through construction. My older Mountain Hardwear Nilas jacket also uses the same mixed construction and I have never felt that my arms were colder than the rest of my body, although the Neutrino Plus generally is a much warmer jacket than the Nilas. I haven't had the chance to use the Positron in actual climbing conditions yet, but Rab gear is among the best and I won't hesitate to take this jacket with me to Peru this summer. I may update after that trip. Many thanks to Campsaver for their great service and awesome prices!