Good question. One for you - what have you tried that did and did not work all that well, or why are you asking?
I would say a 1/4 zip fleece hoody, but I'd freeze my ass off most of the time if that was the case. So have been layering a FL Sawtooth vest with fleece hoody for that "on the move" scenario you give, which obvoiusly isn't just a 2nd layer since I add to it. I think when it is cold, it would be more efficient to use an "active insulation" type layer that is warmer and perhaps lighter than a fleece. To answer your question - best fleece replacment I have found, for me, is an arctyrex atom lt hoody to balance weight, breathability, fit, and warmth etc. I run cold honestly so I'd still have a fleece under it most times.
I've tried doing it a lot of different ways (this is all when cold, like < 20F, when above that no need):
- with a down or softshell vest
- a baselayer + kuiu kenai or patagonia nano air. Using dead bird atom lt is my favorite right now.
- a baselayer + fleece + softshell (works reasonably well, throw puffy over that), fleec + softshell vest
- with FL brooks sweater (worked decent but not great for obvious reasons, wanted to see how it would do with sweat).
- baselayer + FL catalyst (worked pretty damn well, I just don't like the catalyst cut)
- baselayer + sawtooth jacket (this is a pretty $ combo, but sucks in the rain/snow)
I got the new SG Cirque jacket to wear all day when it is really cold and I am cruising around in rifle. We'll see.
Looking forward to the responses here.