RD, that is a pretty good test.
My unplanned test was about 30 minutes riding in sideways rain, and then walking around the small town of Joshua Tree looking for a cafe to get warmed up.
But during that walk, amount of water on the roads was amazing - near to the top of the curbs!
And the next day they actually had Snow plows going down main street to clear the sand that had run into the street!!
Never seen that before.
Not a drop inside the boots. (Or in the super secret prototype Giant Loop soft saddle bags.