Sorry for bumping...just my two cents...
For layering, my biggest issue has been controlling/venting self-generated moisture. In short, I pretty much sweat like a hog. You are probably more efficient on this front than me, so take the following with a grain of salt. Unless it is very cold/windy, I can't skin in a hard shell without soaking myself. Also, since I'm a bit of a curmudgeon on gear I will not buy a shell layer with insulation permanently attached.
So, basic set up:
Generic softshell pants. These get tucked into the velcro power straps on top of my ski boots so that snow does not get in them. Essentially a poor man's gaiter in this case. Since this generally means generic Shoeller type fabric, when cold out I will back up with a base layer underneath. Vents very well, but relatively poor wind & moisture resistance.
I always carry a set of hard shell pants with me. Not because I always need them, but as a 'just in case' item in the event I need to bivy/spend a lot of time helping someone else out. I will be the first to admit this is a 'Justin Case' decision, and one that others would evaluate differently.
I have an older super set of ArcTeryx bibs
https://pro-sport-expert.com/best-ski-bibs/ that I take with me when I foresee wallowing around in deep snow. They have full zips on the legs, tough exterior, and weigh a ton. But they rock, are very tough to rip up, and pretty resistant to external moisture.
I have a much lighter set of PU coated hard shells that I carry with me on days where I don't foresee much wallowing in the snow, nice forecast days, etc. These are pretty much disposable items. They are pretty easily torn up (and patched), much lighter than the bibs but still have full zips on them.
So in the end, if I had decisions to make over again...
On YouTube there are a lot of interesting videos on this topic, I will share with you, one of them, hope this will help someone. Good luck
https://www.youtube.com/watch?v=7nUPhI38-9c
