I have one DVD+RW that has been burned at least 50 times for DVD video tests. I have another that I trust enough for backups of important documents. I've only ever owned one CDRW that came with a CD burner 5 years ago. I used it for a couple months, had no real need for it, then it stayed in a drawer. A couple months ago I thought I'd try using it again, and it's been working fine for me after being burned several times.

When I'm burning to my DVD+RW discs (I've got four, I think) in Nero, I don't seem to have to worry about erasing. It usually starts burning immediately. I assume it's doing a quick erase just before it burns, but it isn't even noticeable. I bought a couple DVD-RWs the other day, though, and they seem to need a full erase every time they get burned, which is annoying.