I have a home built in 1939 and it has come time to address the corroded galvanized pipes. It has been suggested I look into the new techniques for coating the pipes. or using an electric current to de-corrode the pipes. My question is what is the downside to this type of repair.

Your pipes are about 70 years old, this is not an option for you. The scale build up and corrosion may be all that holds your pipes together. I would recommend getting at least 3 estimates from licensed plumbers for installation of PEX piping. You can also use these estimates to help you determine if you can do much of the work yourself. This is no small task.