Arcteryx jacket options

I’m looking to buy either a proton lt or an atom lt. I generally climb alpine routes and I’m looking to get something synthetic to either pair with my down or replace it on warm days. Let me know if you have any experience with these! 

Proton vents moisture better and is warmer than the Atom in my experience

Look at the Proton lightweight hoody 

Also the Nano Air LHH was just re-released, definitely something to consider 

I'd go with the Proton over the Atom for climbing. The fit is better suited, the materials are more breathable and it doesn't have the stupid fleece panels on the sides so is a much better stand alone piece. 

I climb in a Proton regularly and am very happy with it; just takes some tenacious tape every once in a while to deal with tears--the outer material is fairly delicate.

Own both. Proton LT my most used (best) coat ever.

+1 for the Proton.

Going against the grain here. I've owned both and the Atom was easier to climb in due to the fleece side panels giving better stretch for arms over head movement. The proton tended to pull up out of the harness and bunch up where the Atom didn’t. 

Gamma

Victor Machtel wrote:

I'd go with the Proton over the Atom for climbing. The fit is better suited, the materials are more breathable and it doesn't have the stupid fleece panels on the sides so is a much better stand alone piece. 

I’m looking to use it in the winter as well as a mid layer and a belay jacket. Similar to what Colin Haley does and layer it with my down so its thinner, the breathability will just add to it’s versatility. Thanks for the suggestion!

You don't really want a belay jacket to be breathable, because breathability means limited wind resistance.  Belay jackets are generally made from materials that aren't breathable for this reason (and others, such as being filled with down).  Note that Colin Haley uses a Nano Air (breathable, like a Proton) for his midlayer, and then uses a Micropuff or DAS Light for belaying (not breathable).

Both jackets you mention are good jackets, but it's not clear that they are the best thing for your use.  There are also great jackets from other brands worth considering (Patagonia, MH, Rab, etc.).

The Atom LT is a very old product (although it does get minor revisions every few years) and while it's still an amazing all-around jacket, it's a bit outdated compared to the Proton LT, which has almost identical features, but is slightly more breathable, slightly trimmer, and slightly warmer.

Do note that there's a 40USD price difference (Atom LT at 259USD and Proton LT at 299USD). If you're mostly wearing it around town, then the Atom LT is probably just fine - but for climbing and moderate/high-output activities in cold weather, then the Proton is the way to go.

If you are belaying though, you want static warmth with less breathability - look into the Nuclei FL or Atom AR (or other brands).

Zheng Zheng wrote:

The Atom LT is a very old product (although it does get minor revisions every few years) and while it's still an amazing all-around jacket, it's a bit outdated compared to the Proton LT, which has almost identical features, but is slightly more breathable, slightly trimmer, and slightly warmer.

Do note that there's a 40USD price difference (Atom LT at 259USD and Proton LT at 299USD). If you're mostly wearing it around town, then the Atom LT is probably just fine - but for climbing and moderate/high-output activities in cold weather, then the Proton is the way to go.

If you are belaying though, you want static warmth with less breathability - look into the Nuclei FL or Atom AR (or other brands).

I went with the proton LT and brought I put in the Canadian Rockies a week ago for some ice climbing, it got down to -24 c and the jacket handled like a dream!