Layering two down jackets for winter conditions?

if you're not compromising loft, you should be GTG

most folks use a thin-ish (think MB Ultra-light, WM Flash, MH Ghost, etc) w/ a mid-weight (and fuller cut) down jacket/parka

I've used my MB ex-light and MB alpine light parka in tandem- works great and I lets me use my summer jacket w/ my shoulder season jacket w/o having to buy another winter one

Heavier and more complex, but it should work fine assuming minimal compression of the inner layer.

For me it would depend on will I need any insulation while hiking? Meaning my baselayer plus windshirt is not enough to keep me warm, so I need something extra while I hike. For me that would probably be 20's and below with a fair amount of wind. In this case my insulation layer would be a thin synthetic layer like a Arcteryx Atom LT as opposed to down. At camp I would then use: baselayer, Atom, Down jacket and Rain jacket.

Heavier down is better if I only need for camp and don't need any insulation for hiking.

For the sub 0 temps thats a different game and I just stay home. Others on this site will have a lot more info on these conditions.

youll be fine … i nestled a down vest, synth puffy AND a down puffy belaying today …

for a rough guide on how warm itll be … take the total down fill weight (assuming they are 800+) and then look for a similar jacket with the same amount of down

its one of the best ways to save money if you already have the gear you need …. same with bags

it weights a bit more … but then one just needs to lay off the cheezy poofs for a month to make up for it ;)