From the pix I can find of the Phase SV, it looks like the old expedition weight Power Dry fabric. I'm sure that it wicks and dries well, but a fairly heavy base layer material.
The Power Dry HE is a different ballgame. It has grids that are heavy material alternating with lines of very, very light fabric that dries and breathes like crazy. I can't imagine that there is any comparably warm base layer that wicks, breaths, and dries quicker. It really is fantastic for high aerobic/sweaty cold weather activity.
Here's a close up photo of the inner surface of the Cap 4 fabric I posed a while back:
