For stalking I assume? I use the Sitka core heavy weight hoody. If wet I use my jetstream. The hoody is much more quieter than the jetstream IMO. No experience with the two you are interested in.
No experience with either of your options but I use the kuiu peloton 240. It cuts wind better than the guide jacket and since you said no rain I don’t see the benefit of the rubicon. Merino does nothing against wind so I’ve never understood the possibility of the sawtooth for an outer layer
You may want to take a look at grid fleece layer. Those temps pretty common during late blacktail in Oregon and I run a light to mid weight merino base layer and a grid fleece over it. It's very quiet and keeps me plenty warm.
The first lite catalyst is crazy nice. Super versatile. I’ve been using it all fall in northern Minnesota and it’s been great. To be honest when it arrived, I was more than a little skeptical. I didn’t take the tags off for over a week. The catalyst has kept me warm in drizzle, I haven’t sweat a lot hiking for grouse in it, and it blocks wind better than my marmot soft shell. It’s worth it.
I love the FL Sawtooth over a lightweight merino or synthetic base for ~50 degrees and no precip. Super comfy, a little insulation in the right spots, full zip to help regulate body temp, quiet enough. If the wind/rain kicks up, or I go stationary for awhile, I throw a puffy or shell over the top.