ZPacks water resistant down or 900 fill?

I went for the 900 in an order from them a few weeks go. This was partly due to the fact that most of my trips are in manageably dry conditions so I don't need a "synthetic substitute" at the moment.

More importantly, something that expensive I'd like to last for years, but I was reading that it has not been absolutely established how well the treated down will age. I don't know how warranted those concerns are, but some more data to add to your decision.

The only place I have seen this issue discussed is here (scroll down to the end of the article):

http://www.outdoorgearlab.com/Ultralight-Sleeping-Bag-Reviews/ZPacks-20-Degree

but I really didn't research the issue of aging/long-term durability of the treated down, as the paragraph in the article was enough to bump be firmly over the low barrier into the 900 camp. There are bound to be people who know all about this here to report on the latest conclusions.

If it's not broke, why fix it? Has Western Mountaineering or Valandre or Feathered Friends gone with DriDown or DownTek? They seem to be at the cutting edge of down sleeping bags and I'd be interested in their opinions.

For more see—
http://www.trailspace.com/blog/2012/01/26/brooks-range-downtec-mojave.html

I have a Zpacks twin quilt with water resistant down. I chose the water resistant down because I had the quilt made with a Nobul1 inner and outer shell, which is much more breathable and perhaps less water resistant than the heavily calendared 10D nylon Zpacks offers.

I have noticed that, in contrast to other down quilts and sleeping bags I've owned, the water resistant down wants to clump (when dry). I store it hanging in a dry closet, and I fluff it gently to distribute the down before packing it for a trip. But each time I unstuff it and give it a few minutes to loft, the down is clumpy again. In the baffles it forms softball-sized lumps with down-free spaces in between. So, I spend ten minutes fluffing it to distribute the down (although it never becomes as uniformly distributed as other quilts I've had). The following night, after spending ten hours in the stuffsack during the day (stuffed to a soft density, not tightly), it's lumpy again.

I would speculate that any hydrophobic surface treatment of down has to involve a detergent that removes the natural oils. I wouldn't expect a polymer to stick to the surface of a barbule if it's oily. It may be that the surface treatment itself just isn't as good as the natural oils at keeping the down from sticking together.

I don't know if this will affect function in the long term.

The main thing here is not to ask the companies peddling the treated down. Sure they are going to put that it lofts 3 times more than normal down when wet(though %300 more sounds more impressive doesn't it?) but I doubt they are going to say "on the other hand…", even if the have put the money into researching the other-hand issues at the moment.

Anyway, its an exciting development, just not one I want to invest $400 in at the moment. Note that Patagonia came out with their limited edition jacket using water resistant down that all sold out or were given away lickety split. When they come out with regular issue products that use it, and back them up, then that might be one sign it has been checked out better for durability.

From everything I've heard WR down is basically a gimmick, or at least vastly over-hyped. At the margins it might reduce the the down's tendancy to "wilt" in high humidity environments, but if the down gets wet it gets just as wet.

Prolite Gear have a few youtube videos basically debunking the original adverising video where they agitated down in water and the dry down floated where the regular down got saturated and sank. In the Prolite Gear videos they cut open a jacket with supposed WR down and do the same test… both samples saturate completely at the same rate.