Arc'teryx makes gorgeous stuff.

If you've got room to add stuff,

double shakking isn't weird and overkill - I put on 3-4 layers of wool when skiing and then through an arc'teryx shell over it. The ibex long trail sweater gets my vote as the warmest ibex piece. Sometimes I have a fleece over all of that stuff, or something like the icebreaker raven that was just up on sac.

If you look at the ibex climawool pants, I find they're a lot warmer than goretex - a layer of woolies with the alpstars or the backcountry pants is heavenly.

You probably don't need the down sweater or a primaloft sweater.