I just joined the site and am looking for a bus -- so pretty much laying low.
I noticed a lot of folks using Reflectix in their builds and wanted to make sure everyone is aware of its true insulating value. If its installed without an air gap on the hot side its R value is about one -- not what many would thing based on the manufacturer's advertising.
Don't get me wrong, it has its uses. I used some recently on some ductwork.
There is a great discussion here that should clarify where its truly useful and where alternatives are better applied.