I would think the media's longevity factors into the lifetime cost. If the optical media is certified for 50+ years, that essentially means they won't have a n

I would think the media's longevity factors into the lifetime cost. If the optical media is certified for 50+ years, that essentially means they won't have a need to recopy data if for some reason they want to preserve it.. for a long time.. I don't know how long magnetic tape lasts, but I would imagine it would be a huge pain to need to keep backing up old tapes to new tapes every X years.