The drawbacks as I see it for using an electronic solution is that 110vac is required at the tank, but in most instances I believe that this is present. These devices only work in the summer (at least for most of the U.S.) unless the hydrant is wrapped in electric heat tape or there is an electric heater in the tank (these present their own problems that I hope to address in a future project).

This is usually the source of the leaking. If it begins to leak you can reach in and turn the little piece of plastic to a new spot, but this only works so many times. There is also no feed back to whether the device is working or not. While there is no reason not to check the tanks regularly it can be useful to have some feedback, a lot can happen in 24 - 48 hours.