David Conners wrote an answer about Arc'teryx Mako Jacket - Men's on November 23, 2011
Thanks Brandon. Reading up on the Atom line it seems that 100gm/m^2 coreloft might indeed be a bit too toasty. I'm imagining skiing in spring with the equivalent of a denali under a shell and that seems like a recipe for a sauna.
No love for the Sidewinder over the Sabre or Stingray though?