this has got to be a troll, people don't seriously try to stretch base layers over ski boots. I refuse to believe that.
I don't like compression layers. I think the compression restricts blood flow, which counter acts the warmth added by the material. They also don't feel good having them squeezing. The compression provides no aid to joint stability or injury prevention. The best part about them is taking them off at the end of the day, this point alone tells me they suck. Down is the complete opposite of a compression style base layer and down is obviously a better insulator. So I want something light, and loose but tight enough to keep the air traps, but not squeezing on my body. As well as moisture wicking and breathable.
Don't tell anybody, but I wear running shorts, they are small and light, and have an inner mesh to hold my junk in place. I don't ever get a wedgie and I don't feel them restricting anywhere. Thin ski socks. My pants have a thin fleece liner. I wear an UA baselayer 3.0 shirt, with a patagonia capilene 2.0 over top. Shell jacket. I'll ski comfortably down to -20c/0f like this. When I start to sweat, I open the zipper on the Patagonia shirt, as well as the pit zips.