I'll send a piece out sometime this week.
I have a NeoAir I use sometimes (it's narrow and a little loud, as well as longer than I need). I sleep with that silver side down, so I suppose an aluminized bivy would just duplicate the NeoAir's radiant barrier–prob. add nothing.
I just got a Exped SynMat UL 7 that I think I'll like a lot more than the NeoAir–I don't think it has a radiant barrier, so maybe an aluminized bivy or groundsheet would add something.
Or maybe just look shiny.

