Well I can answer my own question now and report that they’re great for skiing. I’ve just been for 6 days skiing. For the first three days I wore my normal (expensive) Eider ski pants, for the last three days I wore the CoLab jeans, both with thermals underneath. I didn’t notice any difference between the two pairs of trousers.
There was a lot of snow around this week so I got snowed on on the lifts and was in deep powder a few times (sometimes deliberately, sometimes not). They stayed warm and dry on the inside with snow and water just shedding off the outside.
One thing that did worry me, with a button fly and deep powder (or windchill) was ‘chilly willy’ but I’m pleased to report no issues there.
Nothing much more to say for now. They just worked.
I guess I’ll be looking to see how long the proofing lasts now, particularly as I’ve not washed them yet.