No problem with washing a down comforter or pillows. Key is, they have to have a fine lining or strong casing, not anything that's been worn by sweat, or weakened with age. Be sure to use the gentle cycle, no bleach. When washing machine is full (water), place the comforter, tightly rolled, to minimize air pockets, into washer. Be sure comforter is well balanced and water covers entire item. Close lid. After wash cycle is complete, remove and place into dryer. It helps to place a couple of clean tennis balls inside. You can also get special soft, spikey rubber balls at Bed Bath and Beyond for down washing. You'll probably need to set dryer for a good 1.5 hours. You don't want to remove item if you sense there are still clumps of down in any of the "pockets."
The same process will work with down pillows. You'll definitely loose some down feathers, but loss is minimal. I've had the same comforter for 20 years, and it feels like the day I first bought it!
