About the discussion over WPBs when the DWR fails: I don't know if failure of the outer DWR treatment will allow leakage; but using detergent is not the way to find out. Detergents and many other substances will 'contaminate' the WPB membrane and allow water to come through. I once did this by spraying a silicone spray on an early edition of Danner GTX fabric boots - they leaked so badly just from high, wet grass, it seemed like they were not just failing, but actually attracting the water. This subject was discussed in Alan Dixon's article here:
I do know, as several of the above posts point out, that failure of the DWR treatment, and the resulting 'wetting out' of the garment will prevent water vapor from passing through it, and eventually cause the wearer to be soaked with moisture from perspiration in many conditions.
Usually such conditions also carry the greater threat of hypothermia, so being soaked from inside can also be dangerous; in that when you are soaked, heat rapidly disperses. Soaking from outside is probably worse, though, because colder water is continually moving from outside, into and through the garment. That's where I agree with David Ure 100%.
I have had several close calls with hypothermia, the worst being in kayaks on large lakes during very cold rains in the fall. While a GTX pull-over, along with a spray skirt, did keep me from being totally sopped after many hours of paddling in the rain, I eventually reached the point where I knew I was in serious trouble and had to get off the water. The second worst situations occurred when hiking for long periods during such rains on open, unprotected ground. Maybe they were not quite so bad, because the hiking kept me warmer than the paddling did. These experiences led me to the following conclusions:
> To become familiar with and aware of signs of seriously developing hypothermia.
> To get out of the rain and into a dry place immediately when these signs occur, even if this totally bollixes up the trekking/tripping schedule.
> To carry enough well-protected dry clothing and sleeping gear to get into and warm me up in the dry place, even though this means carrying more weight than I would like.
> To consume hot food with lots of carbs as soon as possible.
The above are far more important to me than how good a rain shell is. Please give them your serious consideration. Thanks.