I would think anything added onto the down would increase the weight a bit. Any change in the ability of down to float around in air may impact its fluffiness. So my question is:
does the exact same weight of fill, one with and one without the coating, make the exact same loft?

Obviously if you use down continuously in cold-wet-humid conditions, any extra weight or loss of loft would be insignificant relative to the advantage of having the down stay dry.

On the other hand, in many conditions (for example, the Sierra) I never had weeks-long cold-damp conditions. You do have to be careful - for example not fall into a creek. But on the whole, I have never had a problem keeping my down dry.

The comparison I would like to see is the best synthetic vs the hydrophobic down.

As for longevity, if it is like my experience with the water-repellants coatings, it would seem that the waterproofing would break down over time - repeated stuffing.


Like OM, I am waiting on more longevity information. I am sticking with what I have right now.