I'd suggest trying XXL...

The Arrakis has features designed specifically for backcountry ski touring, like a probe pocket and wider front pocket for a shovel blade. If these things are important to you, go for the Arrakis. It also has a large side zipper straight to the main compartment (which I don't like, as it compromises the drybag, and I always load from top down).

If those features are not important to you, the Naos is great and is a really clean design, with better & fewer (unneeded) features that most packs including the Bora series and others mentioned below (it's lighter too!). The suspension on these packs is absolutely amazing.

I like the narrow profile of the Naos, but the front pocket is not big enough for a shovel blade to slide easily in and out when it is full. If you're going out in winter, you can still carry a shovel with one handle in an axe loop and the blade tucked under the lid.

The Naos is bigger, by a small margin, but it has way more organizational options, with the lid, and all. The Arrakis has a small zip pocket on the top outside, and that's about it.

Unless you live underwater, or plan on going canyoneering, these packs are pretty solidly overkill. The face fabric is so heavy. If you want the bird, check out the Bora series, or Khamsins. Osprey and Granite Gear also make comparably sized packs that carry well, with much less BC bling.

Personally, I like the Arc'teryx Arrakis due mostly to the fact that it has a couple main pockets, and is a bit wider profile, so I find it easier to load. Both packs are great though, and you won't be disappointed with either one.

I only know Europe
Airlines in Europe have different rules regarding size of hand luggage. Most of them allow around 45-50 litters. My guess would be, yes you can use it, if you don't pack it to the limited.

I don't put a water bladder inside my Naos... Why put water inside the drybag? Just this week the hose pulled off my full bladder after filling it at a spring, dumping a liter before I could catch it. Luckily there's a drain hole in the outer pocket where I keep it.

I do put my bladder inside my day/ski packs, but never in a pack with a down sleeping bag...

The Arrakis IS fantastic. not submersible waterproof, due to the watertight zip that allows internal access. However, it will keep your gear dry unless it is under water. The reservoir hose access is a watertight zip, and it's easy to get the hose through. Super Pack, just used it to ski in BC in a full on snowstorm, and it performed flawlessly!

Umm...I think the question was about compressing the load, not load lifter or load bearing adjustment. The two sets of straps Andrew mentioned are for making the load sit better on the shoulders/hips. Compression straps are for taking up slack in the bag in the case it isn't full. There are straps on the side that could be used for compression, but are really meant for holding skis and other things on the sides. If this pack isn't full, it will not compress down as well as the Naos series.

Yes it does. It has them down along the hip belt as well as along the shoulders for compressing the pack more snugly and closer to your body.