I can't tell you about the bibs. But the Firewall material models are good for pretty cold conditions. I don't know if mine are the 300 or the 200 series. Alone they are good for me down to 35-40 F. When combined with another light insulating tight underneath they are good to 0 F. My understanding is that they are not as warm as the Performance Triflex models. But they are more useful because they can be worn alone or with another cheaper tight underneath to cover a broader range of temperature conditions.