Hi Monkey, I don't really see the point of that piece for various reasons. While weight is a concern for me to some extent, flexibility and highly modifiable systems are even more important. Instead of having insulation under a non breathable fabric, why not have a separate piece, like a vest with very breathable material lining/outer so that if one needs to, it could be insulation also for activity at more extreme cold temps. (think something like Polartec Alpha). I made some vests with 2.5 oz Apex in between very breathable fabrics, and no insulation on the back, for that very purpose. They are quite light in the 2 to 3 oz range. I made it because i live in VA and like to go out during polar vortexes. Where i hike most often, there are often stretches where there's not a lot of elevation gain or loss. So when it's around 5 to 10 degrees F. for the high (or colder), i might bring the sub 3 oz front only insulated vest to help keep my core warm rather than a heavier fleece. Because the Apex is relatively thin, and the fabrics are very breathable, it dries significantly faster than say a commercial synthetic puffy piece. (it's akin to the Alpha concept). Since there is little to no back insulation (i've made different versions), helps to keep my back from sweating and obviously cuts down on the weight. I combine it with a hooded windjacket and a baselayer (either Cap 4 hoody or fishnet most often, sometimes a Rab MeCo or similar shirt). If you don't have a sewing machine or know how to sew, chances are you know someone that does, or have a local business that could do it for reasonable. It's a pretty easy project for someone that knows how to sew. If you are interested in the idea and can't find any of the above, i would consider making one for you for pretty reasonable–35 to 45 dollar range (but please seriously look around first, as i work a full time and part time job).
