DW, the answer is, sadly, you might need everything if you want maximum flexibility... While a synthetic certainly makes more sense as a flexible garment for any random condition, downies have it pretty much all their own way when it's really cold (and it's most often cold when the sky is clear and thus not raining) and/or you're sheltered in your tent. There's not much contest on small packing size for equivalent thermal effect, with down streets ahead.
So even if not getting one right now, I'd keep your radar tuned for bargains on downies as for a winter day out or camping in the cold they're probably the best option for the jobs you highlight.
Also, in the context of having both to choose from, I use the downie a lot more than the synthetic, and when I use the downie it's usually the sort of occasions where extra warmth is really quite significant. The synthetic I usually use as a downhill ski jacket or walking to work on driech, cold winter days, while the downie goes on a lot of camping trips and most winter walks.
Photon Hoodie is a great jacket, really comfy and warm , as long as it`s not really windy and really cold, wind seems to squash the loft out of the insulation, leaving it more like a thick windshirt. Light and packs down tiny, hood is really good too.
It`s no where near as warm as my Rab Summit Down, (that I`m still trying to persuede myself was a good idea to buy! ) but then it`s half the weight and half the size.
