With the temperature range you gave, and that it's rainy and humid in winter, I'm not sure I agree you need a down jacket at all. Personally, I'd go with a convertible jacket - one like either of these:
LL Bean 3 in 1

Colombia

I know that opinion isn't in the majority here, but do that, and you'd likely save enough money to go on half a dozen extra trips, or buy a bunch of other gear, and won't be sacrificing much. Together, both layers weigh more by a large amount (I have a similar ll bean jacket, and it comes in at like 34 oz for both), but often I take only the windbreaker/rain layer, and am fine down to 32F with a few layers underneath. Or if I take both layers, I leave at least one other top layer at home, so the weight factor comes out about even.