Are commercial BRs made like commercial DVDs, or are they more like burned disks? Cuz they're not the same.
And longevity probably varies by media brand, too, much as it does CDRs. (Which brand are you using?)
Storage conditions, of course, are a definite problem for any archival medium, other than maybe flash drives. (Which are how I backed up a lot of my stuff last time around, cuz they're far more durable in the face of environmental misadventure.)