I was given a Patagonia Nanopuff as a gift a year ago, it has VERY quickly gained a spot in my all time favorite list right next to the Paty R1 hoody.
I would really take a look at the nano if your concisdering the Micro.
Essentially for me its a slightly warmer replacement for the really heavy weight fleeces I used to wear, such as the mtn hardware monkeyman, that still packs down smaller and lighter. The other benefit Ive grown to love, that I never thought about, was how well the Nano interacts with the other layers under and above it. The matierial is so slick that it is almost aids in motility rather than hamper, like most heavier insulation pieces do.
And then of course there are all the benefits (and downsides) of it being a synthetic layer too.