This is my second Patagonia synthetic insulation vest. I recently lost, much to my dismay, my beloved ten year old micro puff (discontinued style) vest. My Patagonia vest was the single most used piece of outerwear in my wadrobe. I wore it to work in San Francisco, on countless fly fishing trips all over the west and snowboarding trips. Despite my emotional connection to my old vest the nano puff version is better in my opinion. Namely, it has a trimmer fit and overall lower profile. Anecdotally, it has a bit less insulation than my old vest which makes it even more versatile as a mid layer for those warmer winter days when my Arc Teryx Atom LT is too much and it makes it more practical for fly fishing on summer mornings that end up heating way and result in the vest being stashed in a pack at 11AM. For Patagonia, the fit here is trim which I also like and differs from some of their more boxy generous cut jackets (I see you down sweater and I still don't like your fit). Overall, I couldn't recommend this piece more highly.