I have 2 old down bags that are more than 40 years old. Just in the last few years have they started losing efficiency...but it could be that my old bones are losing efficiency, not the bags. They weren't always stored right. I had them quite a while before I heard about storing them fluffed, not compressed. This winter I bought a 10F quilt and I LOVE that thing.

“In a time of deceit telling the truth is a revolutionary act.”
― George Orwell

It's not over when you lose. It's over when you quit.