I've been using softshell pants since 2006 and have glissaded in the them many times in included the chute in 2007. As all as they are relatively new they should hold out moisture. Like Gore-Tex products, they need to retreated with a DWR from time to time or you will have one really wet rear end.
What I like about softshell pants is their wind resistance, most block about 70%. I have recently purchase a pair of convertibles for use in the Sierra this summer.
I wear softshell materials all winter long. About the only time I use my Gore-Tex shells any long is when it rains or there is one heck of a snow storm.
