I agree with all of this.......
It's not a lot of intentional product testing, more in field use and I wasn't really referring to a Syn/Down layering system as per say.
The Down Syn layering is interesting but difficult to achieve due to compression of any down inner layer. Problematic, but not an impossible.
I was more referring to the ability that good quality synthetics have of being able to dry out damp items of clothing, and themselves, while wearing or sleeping in them. You don't plan on sleeping in wet cloths, and you don't plan on getting your insulation damp or wet either, but it can happen. With down you are done.
That said, I'm not knocking down. Still the warmest, lightest, packable, by all means.
However, I'm staying with a Synthetic for an UQ as my goto for now, when I can afford another trip to AHE.
Presently, with a tarp with a 12' RL, I'm more wary of spray and splatter underneath, than anything coming down from above. I'm sure when finances allow, I'll get a good down UQ, for the fair weather weekenders and short week or less, hikes and it WILL probably get the most calls, due to the weight factor alone. Longer hikes, Thru or Section, if the weather is suspect at all, I'd want the Syn UQ again.
More importantly, I'll also stay Syn with my insulated jacket. Here is where layering, wicking and drying really come into play for me.
Worst case situation? You can wear them in the pouring rain, and you will be wet as a dog...but warm. Wear them long enough after the rain stops and whatever your wearing underneath will begin to dry pretty quickly.
Often I feel that when we get into the Down vs Synthetics discussions, it's always the weight vs warmth vs bulk vs cost equation. I'm just not yet convinced that formula considers all viable factors, or that the superior insulation qualities of down completely nix the warm when wet and drying abilities of high quality Syns.