Clark pockets and "dead air"
I think that there is no such thing as "dead air" in an un-stuffed CJH pocket. The warmth of your back combined with the cooler exterior air has to create convection currents that will eventually chill you. Yes, a hammock with pockets has to be a bit warmer than one without, but I do not believe by much, and certainly will not be suitable for fall temperatures without added fill to trap air. Demo's Wal-Mart soulution is a great idea. I have cut sections of reflectix to bit the six pockets of my 250 to add to the warmth of my 3-S Phoenix. But I cannot say just how much the Rftx extends the lower temp rating.