For the problem with down jackets and sleeping bags has never been with external moisture (precip, or otherwise). Modern shell fabrics are good enough, and sticking things in drybags on under raingear or mitigating shelter condensation simple enough, that getting my insulation actually wet this way hardly ever happens. The only memorable instances involve me failing to screw a canyon keg down tight (Heaps, 2004) or putting a pack with a non-dimension polyant bottom down in a puddle (New Zealand, 2015).
Internal moisture, on the other hand, has been the bane of down insulation, down coats especially, such that a while back I swore them off entirely, save for one massive parka for deep cold. In Montana the normal range in which I use a moderately warm coat is 40-15 F, temperatures which occur 10 months a year, and where sweating is inevitable. I need a coat that I can put on over damp, if not wet, baselayers and both stay warm and get dry. A standard down coat, especially the light ones with 2-3 ounces of high-fill, can do this 1.5 times before they’re just about useless.
On the other hand the compactness and snuggle-factor of down are both high. Additionally, on the vast majority of trips I bring not one, but two insulating layers. One is for staying warm while moving slowish, when it’s really nasty, or in a packraft. The other is for breaks, camps, glassing, and a little extra safety margin. Every time I don’t use fleece for the first application I end up disappointed, so last year I went back to experimenting with down to maintain the integrity of my two-part system without the whole mess taking up a ton of pack space.
First up was the Sierra Designs Better Vest, which has decent specs as well as being from the company that pioneered DWR down (and claims to have the superior product). I was not impressed, both with an absurdly slim fit, and with down which didn’t resist wetting out from inside any better than standard stuff. The Dridown did dry out faster, but even if the fit hadn’t been whacked out I was still unimpressed enough to move the Better Vest down the road.
Next was the BD Hot Forge hoody, whose fit and detailing I continue to be impressed by (hood excepted). The insulation, Primaloft Gold, is 70% treated down and 30% “Primaloft ultra-fine fibers”. I wasn’t expecting to be all that impressed with Gold, compared to normal down, but the way it manages internal moisture has nothing less than shocked me. In this respect performance is so far above pure treated down that I find it hard to see the purpose of the later. For example, on the first day of our August trip my baselayer and windshirt got pretty close to soaked, first because of drizzle and then because of sweat inside a rain coat while hiking uphill with a heavy pack. Camp was at 7000′, it was still drizzling, it was dark, and Little Bear had finally fallen asleep after a lot of crying we choose to just hike through. I didn’t have the luxury of drying out or paying much attention to my own needs. After dinner and getting the tent up I stuffed a hot water down my coat, got into my sleeping bag, and went to sleep. When I woke up a few hours later, my shirts were dry. Not dryer, dry. The Hot Forge had matched a full Primaloft coat in what is for me the most important test.
In summary, I’m pretty skeptical about the utility of treated down, and very impressed with Primaloft Gold. Even if Gold breaks down in a few years and I need a new coat sooner than I would a pure down coat, it will probably still be a worthwhile compromise. For the last few years I’ve been running a head-to-head comparison between standard and treated down, via the standard 800 fill which came in my stock Vireo Nano, and the 3 ounces of treated down I added to the upper third. Simply put, I haven’t noticed much of a difference. There have been plenty of claims about the virtues of treated down, but I think most of them are based on situations which are of little practical importance. As far as a I know no one makes a down blend sleeping bag in premium materials. It’d be an expensive experiment, but one in which I’d be very interested.