I stick with a garden hose when washing, if riding in the downpour we got caught in on our trip to canada didn't kill it ... then the hose can't do any damage. Those power sprayers are another matter, the pressures can lift open dust seals and penetrate into relay/junction boxes easily. Using pressure washers around brakes will force water into puck seals causing corrosion and stuck brake pistons.
The guy across the street with his new truck loves it so much that he power washes it every other day with a portable in his driveway. It's like light sandblasting with all the minerals in our tap water. He was just commenting that the shine was going away on it already, didn't have the heart to tell him why.