> once you add up all these goodies (double wall, vbl, overquilt, nalgenes, etc ...) or
> even use them individually ... you do have to ask yrself is it worth it and the
> fiddling than just to get a synth bag/quilt ...
>not to say synth wont get damp, but you can usually dry off that dampness with body heat and a nalgene
I understand what you are saying, but I have to disagree with the idea that a synth quilt will solve it all. In fact, good down may resist wetting out better than synthetic insulation, as was shown in an article on jackets some time ago. But it gets more complex than that.
Yes, damp down does lose more insulation value than synthetic, but only if it gets to that damp state. If you can avoid that down is better, and good down can be hard to wet out.
Down can be dried off just as fast as synthetic in my experience.
That's just the start. Other wider factors come in. they include;
If you use a good double-skin tent under 'mild' conditions and can keep the inner tent just a little bit warmer than the outside, you may well manage to keep the dew line outside the inner tent. The slight temperature benefit of the inner tent can mean that all the moisture is trapped by the fly. The inner tent can then usually block any drips.
If you have two people inside a good double-skin tent you have a far better chance of managing the conditions as you have twice as much heat supply in an only slightly larger volume. I guess that having three people would be even better, although I have little experience there. Adding an all-night candle can also work by just adding a couple of degrees to the inside, as above.
Even in way sub-zero conditions when there is no chance of 'water' condensing because it goes straight to frost/ice, having two people close together seems to keep the frost line outside the quilt. Plenty of times I have scraped frost off the outside of our quilts without seeing much loss of loft on the down inside. That's over several nights.
One thing I will hold to though: you can't do multi-night trips in extreme conditions with the same UL gear you might use in the desert in summer! The definition of UL has to adjust to the conditions.