Dale sez "A windshirt and light fleece like 100w, R1, or Power Stretch make an excellent and IMHO, a superior alternative to a Nano Puff. The combination is warmer, more breathable and much more versatile."
This make no sense to me.
If it is cold enough to hike in a fleece and/or windshirt I will certainly need the additional warmth of a puffy when I rest and/or at camp. If it is not cold enough to hike in a fleece and/or windshirt (but perhaps some warmth is needed for breaks and camp) then having a Nano Puff jacket/vest (or down shirt/vest) is a lighter/warmer/more compact solution than fleece.
So for me, fleece is a Fall/Winter/Spring piece only.