Washington state? or Washington DC? Whichever, we all need to move there! Apart from the cold of course, in both.I think it is a good idea, however I live where there is 200+ days of sunshine and when it does rain, it is for less than 10 minutes most of the time. The battery would be dead before I needed to use it. Add to that the fact that the screen on the bike causes the rain to go up and over, I just see no need for me to have one.
Now, if I lived in Seattle and rode a sport bike or other naked bike, this would be a life saver.