In response to various points made further up the line:

1. Media DOES matter. Try playing a cheap cassette tape from ten years ago. The shell may have warped; the tape may already be shedding, and the S/N has gone up. Compare that with a top-grade Maxell or TDK, and the difference is stunning.

2. CD and DVD media quality DOES matter. These forums (and others) are full of posts about people who had problems with one media but not another. There are tools that measure errors and which show big differences in media. As media ages, these errors will increase. If they are lower to begin with, it is almost irrefutable that they will last longer.

3. Don't count on migration. Yes, standards do change, and in 100 years we won't have DVD players as we know them. However, computers still ship with 3.5 inch floppy drives, which were introduced in 1985, and with CD-ROMs, which first shipped (although in small volumes) at almost the same time. DVD drives read CDs, and the new HD drives (some of them) will read both. Laserdisc players could read audio CDs. 33 1/3 turntables could play 45s and 78s. Point is, the ability to play will far outlast the media. More important, no one is going to be able to migrate more than a small fraction of all the media they've amassed. Therefore, if you want to play it on some future "plays everything" player, you'll be glad you spent some extra money for good media.

My argument for migration is not for data format compatibility or future "playability", but for media concerns, and for 2 reasons. First, to keep media fresh, second, to keep mediia current. These are established practices. I was in restoration, archival and preservation for years in Hollywood. Also, robust tape backup is a good idea (Sony Pictures likes AIT since it's their format). And while it's true that many of us have amassed huge amounts of media, if that data is important it should be backed up, period. "I have too much data to back up" is not an argument. If you have that much media, then business is good enough for you to invest in the equipment and time to safeguard it.

If "in 30 years, we have a climate shift to the point that temperatures rise 5 degrees. Now in that enviornment, the results would be different than they are today. Or perhaps something happens to the oxygen that changes the enviornment and its interaction with materials" that were to be the case, you'd have a lot more pressing issues to worry about than the state of your recordings.