If you want something warm for active use stay away from down or conventional synthetics and check out something using Polartec Alpha instead. Down and synthetic down doesn’t wick, just holds air between the fibres or feathers or fronds of down, plus it tends to have a double layer of windproof fabric to get vapour through, one inside, one outside.
Breathability is usually just a shorthand for moisture vapour transfer rates. It’s more helpful to just think of it as being a measure of comfort. My experience of down and synthetics on the move is that they’re not comfortable if you run hot because ultimately they won’t allow a damp baselayer to dry out whereas something like Alpha or even a fleece will tend to wick moisture outwards rather than just pass vapour under a positive heat humidity gradient. Or something like that.
The reasons don’t really matter, all you need to know is that something’s either comfortable or not. The slower and cooler you run, the less of an issue it’ll be though.
Something made from Polartec Alpha insulation is good for that
Snap, bingo etc.
If I’m honest, I haven’t tried on a BAD insulated jacket, they’re all pretty good. Warmth, packability, weight, cut and price are a balancing act
Keela stuff is quite ‘bad’ in a poorly cut, badly designed way, but yeah, stuff these days is generally pretty good.
