My personal experience with the Resist down used by Paul in the Underground Quilts (20* UQ) which has been two extremely wet trips is that down will still get wet if exposed to extreme conditions, you cant soak the stuff and expect it to retain loft, which equals insulation, it is down after all. However, the benefit lies really in the less extreme conditions (wind blown rain, heavy fog, etc.) it will reattain more loft, and keep you warmer than untreated down, and it will dry out much quicker. You should still take all the care that you would normally use with down to keep it dry, but you have a little more room for forgiveness. Which I think is the ultimate benefit. Just my two cents.
Its a proven fact that 78.4% of all statstics are made up on the spot.