Would this be more breathable then my Arcteryx Alpha LT? I'm looking for something not as bomber as that shell. More of a summer, alpine piece. I love my Alpha LT, but those Gore-Tex hard shells are only so breathable. This seems like it still might fight off the wind and the rain, and give me a little more breathability.

Your LT may be more breathable, but this might be more comfortable because of the stretch nylon.

I hope I'm not too late to be helpful, but there is absolutely no way that this even comes close to comparing to your Alpha LT or any other Goretex Pro Shell in breathability or any other function. All of the other design and material aspects set aside the reasons this will not be as breathable is because this HyVent 2.5 has 300,000-500,000 pores per square inch whereas Goretex like on your Alpha has over nine billion per square inch. You're right in that hard shells are only SO breathable - this is where construction comes in. Eventually sweat condenses since even the most breathable waterproof material is still a modified plastic bag, the question then is what happens with that condensed sweat. In theory a material like HyVent 2.5 is more breathable than a three layer material because the moisture vapor goes straight through the waterproof breathable material without having to go through something else, but it's still going to condense. With a three layer Goretex Pro Shell like your Alpha this condensation can be wicked through the membrane by the third layer, but this jacket, lacking the third layer, will instead let that condensation continue to condense and drip down your back, impacting breathability and reducing comfort. I hope this answers your question about breathability - if you have any other questions please let me know.

I don't know anything about the jacket you have other than what you could read in whatever description on whatever website. Having said that, this is the most comfortable jacket I've ever tried on. The fit is slim/athletic and is stretchy. The hood, it's a dream and fits like a glove. If you have a large head, I'd be skeptical on getting a helmet underneath it. I had the hardest time deciding between this and the Blue Ridge Paclite jacket. The only reason I went with the Blue Ridge is because of the rip stop material. Truthfully, I'll probably eventually purchase this one as well, I really can't get it out of my head how comfortable it is and it meets my windproof/waterproof requirements.

cph, This jacket is going to be pretty much the same as your Arc'Teryx Alpha LT, just with slightly different fit. Since you want something as a summer, alpine piece, try a softshell that suits your needs (with or without hood, insulation, etc). Softshells are much better at keeping you cool during aerobic activity without losing much waterproofing (though they rarely perform as well against downpours as a good hardshell like your Alpha) For example: http://www.backcountry.com/arcteryx-gamma-ar-softshell-jacket-womens Or: http://www.backcountry.com/arcteryx-gamma-mx-hooded-softshell-jacket-womens Happy trails!