I have seen some various discussions on Arc'teryx shells, and over the course of this year I have had the opportunity to try almost all of them. I hope my experience with the various models on the slopes will help people in choosing which one is best for them. When I did my initial research here, there were bits and pieces of opinions on some models of jackets... I'm hoping to provide a one post review of most of their hard shell line. I am in no way saying that everyone should buy Arc'teryx stuff, this is more a resource for those already interested.
Alpha SV -- this jacket has two large pockets high in the chest, and a storm hood with a high collar. It's probably the highest collar of any of their models. The Gore-tex pro on their SV jackets feels tough as nails, which I'm sure it is. The main issue for skiing in this jacket is there is no powder skirt, and the hood rides tight if you zip all the way up with the hood down. However, the biggest issue for skiers would be how short the jacket is cut in the front, while remaining suitably long in the back. This is definitely an alpine style cut, and most insulating layers would peek out from underneath in the front. It is defintiely cut to layer with a fleece, but has a nice drape to the fabric... Arc stuff definitely looks "athletic". Over the phone, Arc'teryx reps say that some employees ski in this shell.
Beta AR -- There is no SV model in the beta jacket, which means the Gore-tex Pro is just a little thinner. The jacket doesnt feel as "crunchy", but also feels less durable than SV models. The website describes the Beta as being a shorter cut than the Alpha, but in my experience that only applied to the front. There are two large chest pockets and two inside smaller pockets. The Beta covered most layers just barely, but you could easily have fleece exposed to the elements if you were cinched down. Also, there is no powder skirt. The hood is drop down hood, which is more easily worn down when zipped fully, but leaves the neck more exposed I found. Overall, this jacket would most likely also be too short for most people to comfortably ski in. This also has room for layers in my normal size, but retains that "athletic" look.
Theta SV -- This jacket is advertised as their longest cut, and it definitely is. However, that being said, don't be scared off... it's length is comparable to most other brands models and doesn't feel like a dress. The hood is the storm hood style, with that super high collar. When fully zipped you can cover all but your goggles. This is what I was looking for in terms of protection from the elements, and you really feel like you can sit out anything. There are two large pockets in the chest, as well as a small internal pocket and an internal mesh water bottle holder. This mesh pocket would fit most ski goggles, and I think it is very convienant in that sense. There is also a bicep pocket, which I'm indifferent about but it adds to the storage space. The cut in the rear of the jacket covers your butt, which is useful on lift rides. The jacket retains the "athletic look" with plenty of room and length for any layer you would wear. This is by far my favorite model for skiing, and the only one I ended up keeping.
Theta AR -- same cut as above, but the hood is a drop hood config... this I think would leave the neck exposed like in the beta. Also, the Gore-tex is the less thick denier and feels less rugged.
Sidewinder SV -- This is a product that Arc made for skiing. Its cut much less athletic to accomodate layers, but it loses that trim look. The collar is unique, as it has a zipper that runs up and off to the side. The strange thing about this model is that the zipper is a smaller grade which just doesnt feel sturdy enough to be a main zipper. I had no issues, but it didnt feel as rugged as the other models. This jacket has a high napoleon pocket on the chest, as well as two hand pockets. There are two internal pockets, as well as a clear plastic sleeve bicep pocket. I didnt ever find a use for this, but the reps claim its for a radio. The jacket has a powder skirt so is very suited for skiing, and the collar is high but only went to my chin -- not above like the storm hood. The hood is also not one hand adjustable, and is the drop down style.
Stingray -- This jacket is the trimmest cut of all that I wore, and is made of the Gore soft shell material. Its still a 3L Gore-tex but it feels way less durable. Jacket has two chest pockets and a bicep pocket, as well as an internal pocket. It has a fleece like backing to it, which was really annoying when you wore a fleece layer... it kept binding up when i put it on or took it off. It's supposed to be warmer, but I don't feel its worth the hassle.