I've been using my ABS rucksack for a few weeks now so here are a few more thoughts.
First, I've got a base unit with the 18l Ultralight zip-on plus the 30l zip-on. The 18l is a lot lighter, and a good size for day trips without a rope. Anything else and it's really too small. It's (obviously) less bulky too, which makes it a bit easier to wrestle on chair lifts. The airbag system means the sack is much bigger than a normal rucksack of the same load capacity, and the 30l is actually quite bulky on chairlifts. I think this is an advantage of the Snowpulse design - the airbags are in the shoulder straps so the body of the sack is smaller.
The 30l is big enough for rope carrying days and probably multi-day trips, but I've not done any yet.
Both zip-ons are well made - the 30l especially so, with really tough fabric which explains the weight. They both work fine, but I think they could be better designed. Both have slightly odd pockets. The 18l side pockets are really only big enough for map and wallet and if you stuff the main compartment it's hard to get anything in then at all. The 30l top and front pockets suffer the same problem.
Carrying skis on the 30l is easy. Quick, solid attachments. The 18l is OK but I tend to remove all the extras straps to save weight and then forget to take them when it matters!
Overall - despite the gripes - the sack works really well and is comfy even on long days. Initial nerves have gone, even tree skiing, but I still remove the trigger on chairs and in lifts. This is easily done even wearing gloves and there is a neat pocket on the waistbelt to store it. The thought of an accidental release on a lift...
WEIGHT. Yes, it's heavy. At 3kg for the 30l sack it's hard to forget the extra 2kg over a normal sack on long climbs. The 18l is 500g lighter. Really though, I suspect much of the problem is in the mind...does 1.5kg really make a difference? How much does it slow you down during a normal day? Could you fail on a long skin because of it? Can't see the racing types going for it though.
The other big issue is risk compensation...or taking bigger risks because you're wearing an ABS sack. Hard to tell of course, but I'm sure we're all guilty of this. Would you ski the slope without an ABS sack? Without a transceiver? On your own? In an ideal world of course you only ski stuff you'd happily ski alone - the same argument applies to transceivers too - but it's an interesting question and worth bearing in mind.
One thing is obvious this season - there are a lot more airbag rucksacks around, both ABS and Snowpulse.
