I have taken the Exos 58 as a plane carry-on on several occasions. The key is to remove the floating lid/brane. With this part removed (I take it along as well as my "personal item" stowed under the seat in front of me), and the lower compression straps cinched slightly (reducing the depth by ~1in), the pack fits the 9x14x22 size standard specified by most airlines. I even had someone stop me and make me put the pack in one of those metal boxes that carry-ons have to fit in; it works.
This is a phenomenal piece of gear. With the exception of my balaclava, this probably gives the best warmth to weight of any gear I own. I'm 6' and 165lbs; the medium fits me great with an athletic cut that fits under a shell and over a baselayer. The sleeves were a little tight on arrival, but have loosened a little bit and are perfectly comfortable and not noticeable.
The down is really nicely distributed (with the thickest insulation being around the head and neck, where it will give the most warmth), and the shell fabric has a nice feel and is fairly durable for this clothing category. The warmth is simply amazing. I'm a pretty warm guy (I use my 15 degree sleeping bag down to 5F), but this jacket is great. Combined with a Cap3 and hardshell, I have been warm down to ~0F. I would estimate wearing this jacket inside my sleeping bag adds at least 10 degrees to the rating (I was warm down to -15F).
I really like the no-frills attitude towards features as well. The anorak design, the kangaroo pocket, and the elastic hood all save weight but are highly functional. You can tell that the designers put lots of thought into crafting a piece that has the features you really need, but keeps the weight as low as possible. You can't argue with 8oz.
I got the excalibur/vintage, and even though purple buttons aren't really my favorite, the functionality of this jacket more than makes up for it. When you take into account the reasonable price (especially on S&C!), this jacket can't be beat. A+
How windproof is this jacket? There's nothing in the item description about windproof-ness, even though it's listed under the windshirts category. Is the level of wind protection comparable to other ultralight windshells (e.g. Montbell Tachyon, Montane Featherlite)?