These gloves fit true to Fast House's other gloves. The fit is a good fit too - they feel good on the hand. Grip is better than I expected out of a thermal glove and by that I mean they have good grip, bordering on great. I don't suspect these gloves will see use by me in any race situation but I wouldn't worry about them if I did race or ride super aggressively with them.
They work well for me in the mid-40s and up if I use them on the road. Probably would be ok down to 40 on the trail but I wouldn't want to go lower than that. That is me - others may be comfortable using them lower. My only complaint about them, and probably why they don't work as well for me below mid-40s, is that they have a super thin material on the sides of the fingers that allows too much cold in. I am sure the thin material is required for the fingers to be able to flex. Trade offs. I get it. Especially since these are targeted at mountain biking. I do more road riding in the winter out of necessity because my trails don't do well in the winter unless it is really cold, or really dry for a long time. Anyway. Long and short of it is these gloves are great - fit well, grip well, thermal well. If you're on the fence - go for it.