I had a couple of the Thermarest Neoairs when they first came out- very light and pretty warm (r 3.5), when the Xtherms (r 7) came out I got a couple for winter camping. After about a year I ended selling the Neoairs as the Xtherm didn't weigh that much more- now I use the Xtherm year round, in the dead of winter I'll add a closed cell foam pad underneath
