I bought a synthetic quilt last year and was glad to have it on a couple of occasions over the winter months. A high camp in Wales in heavy clag, snow and wind meant everything inside my Duomid was saturated, if I’d had one of my down quilts it would’ve made for an even more miserable night than it was. In hindsight the sensible thing to do would’ve been to drop a few hundred metres and find an alternative camp. It does take some pretty extreme conditions to render a down bag/quilt useless but it can happen, more so with single skin shelters imho. Given the fabrics and insulation available nowadays, synthetic insulation isn’t the pack filler and weight it used to be, my -5c quilt packs much better than I thought it would when I ordered it.