Just finished up spending 3 nights on an REI Air Rail 1.5. I bought the long/wide, which is the heaviest of the line. For the first time in my life, I didn't *think* about my sleeping pad all night, if that makes sense. Wasn't sliding off it, didn't make noise when I moved, and most importantly, it was very comfortable. R value is 4.2.
It will be going with me this fall on backpack hunts, no doubt.
Might be old news to some of you, but I thought I'd share my experience.