Honestly I've only worn the 97's once, they're too hot. I always wear the 145's, even down to single digits. I don't sit terribly long in one spot though so usually moving. If I'm gonna sit and glass a few hours I'll probably pack the 97's. The waistbands look thick and I thought would be too bulky but don't seem to be an issue under my pants even with a belt.
I see Kuiu has the 120 Merino in the outlet also. I don't have the bottoms, but I absolutely love the 145 Merino hoodie I have, bought the 120 hoodie and it's not the same, stretches out real bad and saggy around wrists and neck and just feels cheap. Figured I'd mention it since you might be considering the bottoms, dunno if they're the same but fwiw.