Originally Posted by
banerjek
Not if it's designed to rejuvenate water repellency used with breathable fabrics. Gore-tex strongly recommends use of Nikwax with its own products.
This.
There is nothing more futile than thinking you're going to be dry if you spend a lot of time in the wet. Come to terms with inevitability. Besides, you get much wetter when you take a shower.
Most people don't take cold showers in a room that is 45 degrees or less. You don't have to get soaked to the bone if you have the right gear.