Side note: I'm no Arc'terx hater. I have several of their products and LOVE them.
You might also look at the
Patagonia Torrentshell in green, or the new
Propper Packable Windshirt. It's far more "breathable" than a raincoat, but obviously far less waterproof. Super light nylon jackets with a DWR coating but no "breathable" membrane are popular among ultralight backpackers.