I agree, Mouse. I took an early-model BA Insulated Air Core out on an October night when temperatures fell to something between 30 and 35. I was warm on top with a WM Megalite - but I could actually feel the cold seeping up through that pad (or the heat draining down intot he ground from me through the pad, more accurately.)

To the OP: Have you looked at the REI house-brand? Given what they look like, I'd guess that maybe BA and Thermarest (and maybe another maker?) manufacture them for the REI brand. They look to be a bit cheaper, too. Just a thought.