Dan Rwrote a review of Pearl Izumi Pursuit Thermal Cycling Bib Tight - Men's on February 3, 2020
Familiarity: I've used it several times
I've never been quite warm enough on days below 50 degrees and these tight are a big reason those days are gone. I'd say the strengths of these bib tights are the precise fit up and down the leg and the fluorescent safety panels on the calves, which are out of the way but still very noticeable. Given that the leg materials are warm thermal, I'm sure this kind of snug but supple fit is not easy to achieve.
For the price the value is high; the fabrics are top quality. The chamois and bib section stretch are not ultimate but are working fine.
I've ridden these through a fairly mild dry high desert winter, down into the mid-40s through the mid and even high 50s (At that point I switch to knickers). I'm pretty sure they will be fine into the low 40s matched with good booties and serious gloves and other gear for that wind chill.