Having been a recent convert from a sleeping pad to an underquilt, I got to thinking about why folks are so enthusiastic about underquilts. That enthusiasm seems to stem from the "comfort" that results form an UQ versus a pad. Having slept 10 nights with an underpad, though, I was wondering if that apparent "comfort" was enough to really justify all the extra complexity of an UQ. I wanted to get down to a more pertinent question that, at least to me, appears to be more often overlooked - the failure modes. Since the purpose of an UQ or pad is to provide insulation from the air below, I started thinking about ways that the bottom insulation could fail to provide this insulation.

Here is what I was able to conclude regarding the inability of a particular bottom insulation to function:

Underquilt:
- Inadequate suspension along sides
- Inadequate suspension along ends and sealing
- Strong wind blowing a gap or moving the UQ ends/sides
- Improper alignment
- Moving around to cause a gap near the ends
- Moisture inside the UQ

Pad:
- Improper alignment
- Pad moving around (I have not experienced this with my double layer hammock)

To me, it seems the failure modes of the Pad are much easier to fix than those of the UQ - making the Pad a more robust bottom insulation. Furthermore, once the pad is aligned and the sleeper is on top of it, I don't see how the pad could fail - assuming it is wide enough at the shoulders.

What am I not considering or missing?