Considering that backups run at 3x instead of 6x then the Wii DVD drive is actually running slower and much safer. If anything it'll prolong its life.
However RW discs may be harder to read for the machine.
While they may be good for testing, I'd suggest using a good ol DVD-R.
I never use +Rs myself but aparently they work fine to if you set them up as -Rs in the burner app.
If the drive is making noise on that RW disc and only that disc then it must be working hard to read the data.
Try to use a backup on a dvd-r and re check commercial discs to make sure the drive isn't having problems on its own.
My wii, long before the softmods hit, had a drive problem and made loud noises when it spun the disc.
I eventually sent it in as it stopped playing some games and all GCN games.I got it back with a whole new drive (D2C chip one too
). So be sure to check the drive for normal problems.