First, a little about me. I live and hike/camp in SoCal and I'm a three-season person. I spent much time in the outdoors/backcountry in the 70s/80s and just got back to the sport in May 2010. I did four day hikes and two multi-day trips in the Sierras by August and was really revived. My full pack weight on the longer trip was around 35+ lbs. I have been trying to lighten up ever since. I'm a size Medium.
On to the topic. I currently own the Arc'teryx piece, but have never worn it and have read allot about the Montbell jacket. When overnighting, I take four layers: s/s synthetic shirt, l/s nylon shirt (for sun protecton/mosquito's if needed), a fleece (replaced by the Arc’teryx Atom LT), and a Marmot Aegis rain jacket. So, my question is, will the Montbell EX Light, at 5.5 oz. vs. the Arc’teryx Atom LT at 11 oz., be as warm as the Arc'teryx? I don't want to sacrifice warmth for weight. I always take a jacket, whether day hiking or camping. I'd like to lighten up, but also want to be prepared. That means keeping warm if the need arises. I'm not sure how the two jackets compare, so that's why I'm asking. If you have other better options, LMK. I do see the Montbell jackets are on sale and so this is pertinent to me now. And I could take back the Arc'teryx jacket and get the Montbell if that's a solid move. What do you all think?