Really light wind shirts

Check out the TNF Verto. Mine is a couple years old and works great. 2.7 oz for a men's large. I bike to work in mine every day. It sheds light precip well and the breathability is good.

I have the MH Ghost Whisperer (hooded) it weighs in at a svelt 1.9 oz and packs down to smaller than a pack of cigarettes :) I added a shock cord in the hood which put it at 2.0 oz even

It sheds moisture pretty well, breathability isn't as good as my older Houdini (although evidently on par w/ the newer Houdini's) I use mine running when I'm unsure of the weather as I can fit into the small pocket of my running shorts or tights. If I know I'm going to need a windshirt I grab my Houdini

For backpacking where I know I'll be using it regularly, I'll add a few ounces and take my Houdini-breathes better w/ more features

The previous model Tachyon breathed OK, but I'm not sure about its most recent version. The Zpacks wind shirt has VERY low breathability which is fine for some folks. Of course, often the water resistance goes up as breathability goes down.

What about Luke's making you one from the fabric of your choice? That way you get features that are most important to you. My XL comes in at 2.1 ounces including hood and waist hem adjustment, plus full zip.

Ryan

There are two versions of the Tachyon from MB:

Tachyon Anorak – 1.9oz, hooded, half zip.

Tachyon Jacket – 1.6oz, no hood, full zip.

I have the Tachyon jacket but I would only bring it for the absolute lightest possible trip, it's not very comfortable. When it gets dirty it sticks to the grime on your bare arms and that feels awful. It feels like a plastic grocery bag. For Colorado it's fine since you never need to wear it for long. I still have it, but I usually reach for my Houdini nowadays.

In theory, there's no reason the uberlight fabrics can't have as good a DWR as anything else. The Quantum GL Rab used for the Xenon was excellent in that regard.

I worked with some Argon nylon fabric recently, and when i was working with same (to boost warmth of a quilt), thought that it would make a great uber light, mostly trail use only windshirt/jacket.

If i did so, i would probably wash out the existing DWR and apply a one sided DIY EPIC like silicone coating to decrease breathability a bit, and to have a longer lasting DWR.

I have the new Zpacks Wind Shirt. LOVE IT… Mine has handled mist and wind very well with good breathability BUT I have only hiked 2 miles in it so far and I do not sweat like a guy because I am a Girl. Your mileage may vary :)