…and single wall vs. double wall.
OK, complicated systems, these winter clothing-sleep-shelter systems can be.
This thread is motivated by two different philosophies that are somewhat motivated by alpine climbing techniques, so consider that as a context/disclaimer for this discussion.
Mark Twight (in Extreme Alpinism)proposes the use of a pure synthetic system of clothing that has maximum breathability, on the rationale that (1) you’re going to get wet from within (sweat) and (2) you need to have breathable materials to dry your system out every night while sleeping. So, think Polarguard and highly breathable microfibers as shell materials.
Conversely, in a recent letter on the McHalePacks.com website Dan McHale emphasizes the necessity of having a waterproof breathable shell on down insulated materials.
Note that careful reading of these arguments indicate that McHale is not opposed to synthetics, but Twight certainly is opposed to the wpb shell-over-down philosophy.
McHale’s argument focuses on controlling external moisture from entering the system and maintaining a very tight microclimate to move sweat vapor through the system, while Twight seems more concerned about internally generated moisture (sweat).
Having used both systems, I’ve seen them both work reasonably well.
The questions I pose for discussion here are:
1. At what point/condition does the breathable-shell/synthetic-insulation system become more advantageous than the waterproof-shell/down-insulation system? I have to ask this question because we’re still looking at significant weight savings, especially for “winter weight” items, of down over synthetic (that gap is reduced for 1/2/3-season systems).
2. Is there utility for system components based on waterproof-shell/synthetic-insulation?

