In reply to weefish:
Good points: weighs absolutely nothing, packs really well, back is floppy but the foam is pretty resilient, fabric is super tough, made to order so can be customised, waist belt is easy to get out of the way of harness, ice axe loops are completely idiot proof, rope strap on top of sack is behind the drawcord instead of over the top of it (can't believe how many bags get this wrong!), it packs down really small to climb with.
Bad points: I had to extend the zipper on the top pocket to make it easier to handle with gloves; took two minutes to do this using a bit of tat. Back system is slightly sweatier than a complex one. Hip belt is not padded, which might make a difference with big loads in the sack.
For reference on size, I've just come back from Italy where the sack was used for ice cragging. It fitted in it: belay jacket, softshell jacket, spare gloves, harness, two 8 mm 60 m ropes (one on outside of bag), crampons, helmet, 500 ml bottle, plus emergency gear in the lid. That was quite a tight squeeze but not too difficult. When my bigger sack wears out I'll definitely buy one of the big Aiguille sacks and won't even bother looking at anything else.