In reply to TobyA:
>.... I'm normally quite good at seeing the basic design logic of camping and climbing gear - but I can quite get my head around why you need insulation inside an air mattress once its full of air.
>
> Anyway - as I get older, comfy looking mattresses look ever more attractive so had been quite tempted by one of these!
As I understand it, the insulation in the Exped versions is to prevent the air circulating and the cold air from the bottom of the mat replacing the warm air at the top (which you will have warmed up with body heat).
How effective it is I don't know. I assume it would be more effective than having insulation in just one area - but how much of a difference you would notice, I have no idea!
Hopefully someone with some first hand experience will be able to give some more accurate info.
Si