I had good luck with them for many years, but I usually use them for shoveling the drive or stomping through the yard. My biggest issue was width, I have a EE width foot so for many brands it ends up being a compromise. I had to upsize to a 10 in the Sorel and even then, the boot was very tight in the toe box. That ended up compressing the liner more than usual and making a cold spot near my toes, added fatigue and soreness, and mostly limited them to short jaunts.
As far as warmth goes "in general", I had no issues with them. The liners were very good, and you could quite easily add additional insulation under them if you really needed. But they did get cold where the liner was heavily compressed.
I ended up moving away from them to a Kamik which did come in a 9.5ee size, even with only 400g insulation the improvement in fit and comfort was a total game changer. An extra felt insole and medium weight Smartwool socks makes -40 no big deal and I can always lighten the sock or remove the extra insole if I'm overheating.