How reliable is CD-RW really??

[jdiffend]

I've owned several CD-R or CR-R/W burners since 1994 and have burned several hundred disks and here's what I've observed (many of which have nothing to do with your problem):

1. If there is a problem in the source file the software doesn't always detect it and you will always get a corrupt disk.
2. Not all CD burners are created equal.  I rarely ever have problems... my friend has nothing but problems.
3. I started getting errors on disks right before a CD burner died.
4. Some CD-R or CD-RW brands stink... they are best used as coasters.  
5. CD-RW disks seem to be more sensitive to scratches and dust.
6. Multi-session disks have a lot more problems.  (probably driver support issues)
7. Some things just don't seem to work on CD-RW disks... you have to use a CD-R.  

[jdiffend]

I've been worried about this recent concern over the long-term stability of the CDR media

I wouldn't worry too much.  I burned a few audio CD's back in 95.  They have been carried around in my car for years and they still work fine.

If it really worries you, buy a different brand than the ones you already used and burn a 2nd copy.  One of the two should survive over 5 years even if one brand is bad.  

If you have some non-copyrighted stuff that other people would be interested in you could share it on a peer to peer file sharing service.  Someone would be bound to have a copy if you ever needed it.