I had the Arete 2 but replaced it with a Lowe Alpine Attack MX 42+10 (superb sack, better design and workmanship than the Berghaus). The easy to remove hip belt should be great for winter climbing and the shovel/crampon/whatever front pocket very useful.
However, after just a few days use I stumbled upon a Haglofs Rand 48 which is even better, so bought that. (Better that is for ski touring, though the Attack MX was pretty good for touring too. The Haglofs is not quite so good for technical climbing though: the MX would be better.)
Guess I should really move the MX on, the sack rack is looking over crowded!