Arcteryx soft shell and layering systerm: New winter hiker needs advice

If it's cold enough to warrant a thick insulating layer, you won't be needing your waterproof layer for anything other than warmth. If you've been wearing the waterproof layer in that cold of conditions, chances are there'll be some ice/frost built up on the inside of if where it isn't warm enough to transport the moisture through the fabric. I you put you down over that, it will melt and the moisture will migrate into your down.
I put my gortex hooded jacket over the insulating layers for that final bit of warmth if needed.
Yeah, it's fun, but for the 30 years I've been at it, I've never had everything just right. Getting closer though. ;)

I don't have anything waterproof/breathable in winter. When I get to go to the mountains in winter it is usually very dry, lots of snow but dry. I am talking the west so I don't know about the east coast conditions.

If you could get rain and below freezing temps I would not take a chance without one.

For the PNW, I use:

Icebreaker baselayer
Patagonia R1 hoody
Rab eVent parka
Feathered Friends Helios hoody down jacket
Arcteryx Gortex rain pants
Gaiters

I've found this combo to cover all my hiking/camp needs.

I do have a dedicated windshirt, but the eVent parka has taken over this duty. I also own a Marmot Driclimb shirt, but only wear it around town. My only softshell is a very breathable, lightweight pair of Arcteryx pants.

Is there any difference between something like a vapor rise or driclime smock, against a 4 oz windshirt with power stretch or mid weight base layer under it? I think the second option would defiantly be more useful for summer hikes in the same regions like the White mountains, where you only need to trap a little warm air while your moving. It also opens up the soft shell pants to stuff like the montbell stretch wind pants and a base layer underneath, and then investing "weight" into a nice thick waterproof pant for glissades.

…I've wondered about that too Jonathan.

The RAB Vapour Rise/Montane Duality tops are equivalent to a thin fleece and a pertex windshell, so the latter combination is far more versatile.

However, having said that, if it is going to stay cold enough I find the 'one piece' solution to be easier, even though they are normally heavier than two seperate items. The problem is will it stay cold though – I've managed to get this wrong too many times!

My subjective experience is that I stay warmer in the lower temp range with the Vapour Rise than with a separate base / windshirt at the same weight. This could be in my mind, but I think it's real. I have wonder if having them sewn together cuts down some convection cooling due to billowing of the fabric. The other advantage you have one less, or in some cases two less layers to manage.

Doing a separate base / windshirt certainly provides more options… especially in warmer conditions. In fact, for spring, summer, and parts of the fall I bring a base + windshirt and don't bother with a "soft shell"