Hi my test of the Lamina 20 was at home in my house on a chilly night around 40 to 48 fahrenheit. I was not using a tent but I used a thermarest pad. To make a long story short there was plenty of room which was nice and the upper body insulation was effective. However from my knees down I was cold and my impression was that there was just not enough insulation there, especially in the foot box area. So imagine if I had been on the trail instead of my house and snow camping in 20 degree weather, the supposed rating for this bag, I never would have slept at all.
I think compared to a Marmot synthetic bag which is a bit bulkier and heavier, the lamina just does not compare.