>>1600321>>1600384Dunno what you mean by "regular fleece". Wool comes in all shapes and sizes, same with fleece.
Either way, my experience is that "high loft" fleeces require a shell (gore-tex jacket, windstopper, etc.) to make them fully effective. They work by trapping air and creating a buffer zone where all that fluffy fleece is. If you have nothing on top of that, then the slightest amount of wind will rapidly negate the advantages of that kind of fleece.
Also, Polartec's own website says that High Loft offers the best warmth to weight ratio, and based on personal experience I'd have to say that's probably true.
