Hey GrayBear, for "above treeline," I'd assume conditions of substantial wind (30-40 mph) and cold temps (0-10 degrees above) with low visibility. In my experience, this is pretty standard for the Presidentials in Winter. Of course it gets a lot worse, but that's beyond the scope of your question, I think, and you do see occasional days that are "nice," but you probably don't need our advice for those days.
First, when I'm above treeline, I find it's generally more difficult to retain heat than it is to dump it. This is the opposite of below treeline. Below treeline I have to be constantly focused on not getting too hot and sweating. Above treeline, because it's so windy, even if I'm wearing quite a few layers, I can just unzip a pit zip, or the sides of my wind pants, or my crotch zipper, or the zipper to my jacket and the cooling effect is huge. Modifying my pace has a similar effect. Furthermore, stopping to take off the wind jacket in order to add another insulating layer can be really painful and possibly dangerous (this is when gloves/mittens blow away, or that shell jacket blows away... and then you're really screwed. The hands can go numb very quickly too, which slows the layer addition process considerably). Furthermore, most people, when they get cold, get stupid and lazy. I'm not kidding, this is demonstrably true. This is a real problem above treeline. For example, maybe you'd be a lot safer on that upcoming snowfield traverse if you stopped and put on crampons. But your (stupid and lazy) brain says, "So much work to unclip the crampons...I'll probably be fine." Or maybe you really should add a layer. But again, stupid, lazy brain doesn't want to stop and take off the pack and dig out a layer, etc. etc. Of course if you have to do something that actually requires brain power, like taking a compass bearing in heavy wind... Better have a nice warm brain. For those reasons, I tend to err more on the side of TOO MANY layers rather than too few. Again, this is the opposite of my approach below treeline. And again, there's the caveat that it's easier to dump heat in cold, windy conditions than it is to dump heat below treeline.
My "go to" system for the above conditions consists of:
Bottom: synthetic underwear, wicking long underwear bottoms, microfleece pants, and Gore-tex wind pants over everything. [edit: occasionally I'll add an additional ~100 weight fleece pant under my shell pants if it's very cold (below zero)]
Top: wicking long underwear top, wool sweater, fleece vest, Gore-tex wind jacket. [Edit: if it's very cold (below zero), I'll add a light Primaloft jacket under my shell.]
Accessories: Koflach boots, plastic bag VBL's under a single pair of heavy Smartwool socks, OR Crocs gaitors, 300 weight fleece gloves, Gore-tex shell mittens, thin balaclava, neoprene mask, fleece hat, goggles (pre-treated with Cat Crap or other anti-fogging agent), hood from my shell jacket cinched securely.
Extra in pack: spare pair of goggles pre-treated with anti-fogging agent, thick Primaloft gloves that fit under shell mittens.
[Edit: just noticed my avatar shows pretty much exactly this system. That picture was taken near Sphynx col, heading towards Clay. The picture was taken in a protected spot, but conditions were zero degrees and getting colder with winds sustained at 60 heading to ~80 as we passed over Washington.]
This amounts to a lot of layers, but again, I find it VERY easy to dump heat in cold, windy conditions by simply unzipping an outer layer or two on the uphills. I have never worn my puffy while actually hiking, FWIW, but I do consider it an essential piece of emergency gear. Also, I know maybe 1 or 2 people who have the expensive (Ibex) wool base layers and rave about them constantly. I would love to have a set, myself.
Capillary action in wicking clothing does not assist vapor transport--I would say its a looser weave. 
