Just to be a contrarian I'll suggest a synthetic bag that may be worth checking out vs the down alternatives depending what you budget is.
I use a Outer Limits Trek Smart 2 (-5) for all my tramping and have found I have stayed warm even in a tent in snow on the Ruahine tops. (Haven't tried it in winter in the deep south and I do sleep slightly warm.)
It weights 1.3kg which isn't massively out of line with some of the Exped bags (I didn't check them all but see the Waterbloc 600 (-4) is 1.15kg for a medium).
The good thing is you are able to pick up the Treksmart for under $200 ( https://www.outdoorsupplies.co.nz/Outer_Treksmart2.html).
I've got a sleeping bag and a jacket from this outfit in Poland, have found them high quality at a good price, easy to deal with:
http://sleepingbags-cumulus.eu/uk/categories/sleeping-bags/down-sleeping-bags
I have a Liteline 400, you could go lighter in that series or up to the Panyam 450 or 600 if you needed warmer. High end 850+ down, very compressible, good price without having to wait for the NZ retailers to do a 30 or 40% off sale.
Exped "Comfort Series" are great for those of us who like a bit of room in their bags. Various weights available
