Down insulation is incredibly warm for its weight, making it a great choice if you're riding in bitterly cold conditions or sitting on freezing chairlifts all day. Nothing beats down for warmth-to-weight ratio, so you stay toasty without feeling bulky or weighed down. It's also highly compressible, which is nice for travel or packing light for backcountry trips.
The big catch: down loses almost all its insulating power when it gets wet. If you ski or ride in coastal or humid climates where wet snow is common, down can leave you cold and miserable. Synthetic insulation keeps warming you even when damp, making it the safer bet for those conditions.
Down-insulated pants shine in dry, extremely cold environments—think interior BC, the Rockies, or bitter midwinter days where temps stay well below freezing. They're also ideal if you tend to run cold or spend a lot of time standing around rather than working up a sweat. Just pair them with a quality waterproof shell and avoid wearing them on slushy spring days.