http://survivalinfo.co.uk/survival-...-kit-reviews/523-carinthia-explorer-down-1000
No one want a down bag??
I would go for either the Explorer Down 1000 or the Survival Down 1000 only if I combine it with the Defence 1 Top in order to protect them from moisture, although they say the outer fabric of their down bags (Shelltex) is moisture permeable. Unless you have a Gore-tex bivy.
There is a two bag sleeping system made by carinthia for the swedish army, it reportedly was (is?) quite good. Not centre zip, and I'm a convert to those. A thin summer bag, a thicker spring-autumn bag, and the combo would do -40 C IIRC.
Finnish Army's Defence 4 is quite interesting.
http://www.scandinavianoutdoorstore.com/en/makuupussit-ja-makuualustat/talvimakuupussit/army-sa/