The air channels actually do their job—my kid wore these under snow pants on a freezing hike and didn’t complain once about cold legs. They breathe well enough that he wasn’t sweaty when we came inside, which is exactly what I hoped for.
The high loft channels really do seem to trap warmth—my daughter wore these under snow pants for a full day of sledding and never complained about being cold. Only gripe is they run a bit long in the leg, so I had to cuff them for her.