If you have a lot of parafin wax, melt, pour or dip and peel. Some say it works quite well for the down.
If you deal with a lot of ducks, geese, etc. check out this site. http://www.whizbangbooks.com/ I borrowed a copy of the book and have a friend with an auto tub plucker and scalder. It worked great. Five of us butchered 279 chickens in less than five hours, taking out time for tea . 279 chickens ready to go.
He pasture raises them and sells them periodically throughout the year. Very nice.