The only CDs I've had a problem with were ones that I let get too scratched up. Then, with a lot of polish and trying different drives could get them to work well enough for ripping. I also had a CD-R that went, delaminated but don't know the brand. A gift.
Be careful about RAIDs. They are better than raw discs, but do not protect against fire, theft, accidental erasure (the #1 cause of data loss), and RAID control circuitry going bad (I've actually had that happen). Good you have cloud backup. That could get pricey with my 400+ CDs in flac.
Manufactured CDs have a life between 70 and a thousand years depending on who you read. They've only existed for 30 or so, so whether accelerated lifecycle testing is accurate, only time can tell, literally. You get what you pay for with CD-Rs. Buy cheap and you only have yourself to blame. Taiyo Yuden makes archival class ones for just a little more.
I keep a physical copy and make one if it is a download (like HD Tracks), then a copy to my media server. Not perfect, but better than no backup at all. I'll get a backup drive at one point. The ripping process was time consuming! Just did them all last year.
I hope iTunes doesn't take everything over, at least not until they up the quality. Storage is going down in price all the time, so they should be able to, but the mass market doesn't care, so it's chancy.
Scott
