Actually metal studs conduct heat at a greater rate than wood. There was an article in Fine Homebuilding some years ago exploring this technology and I remember it being mentioned that some contractors of stick frame buildings were doing hybrid const consisting of wood stud ext walls and metal stud int. Specificaly to deal with the heat loss issue of the metal studs.
One option I have wondered about is using metal studs with a thermal break. That is with a layer of rigid foam either over ply sheathing or directly on the studs then strapping and siding.
Or alternatly the same idea using 2x4 wood studs