Thanks for all your thoughts so far -I'm really keen to try them all out, so just need to find a somewhere in UK which will easily accept returns!
facewest.co.uk looks ok...

As you say, my main concerns with the NeoAir is the durability, which is still somewhat unknown, and of course the warmth.
I really like the look of the Synmat with the integral pump - very cool design! Just wonder if it's worth the extra weight and size, and how well fibres survive...!