Gear List

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As far as the R1 goes, It's usually too warm for daytime use. Great in the morning and evening.

Maybe consider adding a more robust top layer (I have a Marmot Precip and a RAB Kinetic) and a puffy bottom bottom layer (WM Flash pants).

personally for me the atom lt hoody is too warm down to around 20F or less on the move … every time i wear it at those temps i sweat it out fairly quickly

a R1 is useful to have, or a cheap 100wt fleece …. you wont need em around 30F, or i wont at least … but drop into the teens and you might find it useful when active

it all depends how hard you will be going and what type of movement … for belayed climbing i can see the atom being more useful … for continuos movement, especially up hill at those temps, less so

try it out in a day hike and see what works for you

I will go slightly against the other responses and say that opt for my R1 9 times out of 10 for cold alpine use. My layering system goes:

-Baselayer: R1 Hoody, it is rather warm but perfect for high altitude, cold weathered days and the zipper is great for instant venting.

-Mid layer: First Ascent Downlight sweater, very warm but not too warm in cold temps when moving.

-Outer layer: Either my softshell or hardshell depending on expected weather conditions.

-Legs: I just go with Capilene 1 or 3 bottoms under First Ascent's Guide pants.

In my pack I will carry a First Ascent Mountain Guide Hoodied Jacket and a pair of FF Volant pants that are perfect for stops, camp, or emergencies. With all of this, I could probably stay warm down to about -10F and be comfortable around +40F.

You said, "mid-30's to low teens while active." Pesronally I wouldn't want either the R1 or Atom Lt (I own both). If it is windy, I do like the R2 vest, which is very breathable and can be worn over a base layer alone or under a wind shirt.