I own two big Agnes bags. The lost dog and the horse thief. The pad as insulation works great. I have the insulated air core pad and it is the best sleep I have ever had while camping. I use the lost dog down to 50-55 and the horse thief below that. I may use some additional padding under the IAC when temps are below 40 but even with that, I dropped a lot of weight with using these bags over my old campmor 20 degree bag.