Jordo,
There are a couple other options available as well. You could run a solenoid acutated off a MSD window switch to control the water (essentially the Banderlog box but not by Banderlog). You could run the same solenoid valve connected to a microswitch on the carb to only dump water at a certain throttle position. You could connect a solenoid to a toggle on the wheel and run the water at your discretion, or you could just pony up for some polished stainless lightnings
In all seriousness, I don't have any 1st hand info on the Banderlog valve. But as a recommendation for any automated setup, make sure the solenoid is "normally closed" and install a valve in front of it, so you can still moderate the water flow in the event of an equipment failure. Better to cook the headers than to hydraulic the motor.
Chris