Would Polartec Expedition Weight thermals or Expedition Weight Fleece be a better mid layer for cold weather conditions? Also, would it be a good idea to add Merino Wool layer on Enduraskin base layers?

I use Merino wool as my mid layer over top of my wick away base layer clothing..The thing I like about it, is the fact that it is all natual,lightweight, still blends in with the natual clour of the landscape, and its quiet..