I live in and area where we don't get a lot of Canada Geese but at the duck ponds in parks we get those big white honkers. Do the feathers offer the same advantage of Canada Geese?
There seems to be a lot of interest in Snow Geese feathers of late. Several threads started in Pow Wow. I think the reason you don't find them advertised or sold is due to the Federal Migratory Act.
There is some history, and lore aroung Grey Goose fletching in Merry Ole England. They have been used, and their water repellancy should be good. But live birds preen their feathers so they stay water repellant. You might have to use waterproofing, but they should be as good as Natural Turkey (grey barred). Look for the large primary feathers, not the short secondary.