those new ultralight ultrathin down jackets?

I use this one: http://jgglover.co.uk/acatalog/Country_Clothing_Saddle_shoulder_sweater_27.html

I usually bring an Ibex wool vest as an additional layer.

I like this (or at least the past iterations of it) as a wool mid-layer:

http://www.llbean.com/llb/shop/70861?page=shetland-wool-sweater-crew

cushetunk said:

I like this (or at least the past iterations of it) as a wool mid-layer:

http://www.llbean.com/llb/shop/70861?page=shetland-wool-sweater-crew

Click to expand...

+1. But it has to be green or it won't keep you warm. I wear mine frequently when Nordic skiing in colder temperatures, with or without a shell depending on the wind. (OK, not so frequently this year …)

Here's my inventory, arranged in increasing order of warmth:

1. LL Bean Shetland sweater, linked above by cushetunk. 14 oz./400 g Does an amazing job even when I'm perspiring.

2. Woolrich Buffalo Check Plaid shirt (23 oz./650 g) or US Army surplus field shirt (24 oz./670 g) (both 80% wool/20% nylon). What to wear when you want to be surprisingly warm.

3. Woolrich Wool Alaskan shirt (30 oz./860 g) (also 80/20). What to wear when you don't want to be surprised by the cold.

4. 300-weight fleece jacket (20 oz./548 g) (almost always worn under a shell, 'cuz it's virtually worthless in a high wind otherwise). OMG, will it ever get cold enough again to wear this?

Using down for a midlayer makes little sense to me, given its compression under a shell and its tendency to absorb perspiration. For the record: I own three down jackets and cherish every opportunity I get to wear them. But that almost never happens on the trail in New England below treeline.

I use this shirt quite a bit and I'm very happy with it; it's warm, tough, and sheds a light drizzle. I wear it hiking, skiing and working in the yard. I find myself moving more towards wool and away from synthetics because the wool garments seem more durable, resistant to branches, snags, sparks from fire, etc.
http://www.sierratradingpost.com/woolrich-north-creek-wool-shirt-long-sleeve-for-men~p~4469p/
I also like old wool sweaters that I sometimes find in thrift stores. LL Bean's ragg wool sweater is pretty classic - i recently got a new zip front version as a gift, and it seems like a great mid layer piece.