Well the new one hasnt been tested yet. It is complete and I think will work well. Last years in Smokies it went down to 22 degrees at night and I had a piece of palstic a space blanket and spare clothes under me. I was in a 20 dree rateed REI Kilo sub bag. I think twenty is pretty generous for the loft of this bag. I slept in long johns and was mostly comfy. I had a thermarest ridgrest in hamock as well. I will test my diy underliner soon. I know it will be warmer than last years. I can always add my fleece and down vest in between. I dont winter camp per say But in Mts in early spring it gets cold at the drop of a hat!