Well I'll tell you this, the Wii has a DVD drive that WILL wear out. I burned the drive out of mine and now use a harddrive only. I would really suggest using the disc drive as little as possible.
Anyway afaik they never did get gamecube backups working really well on dvdr's
Think of it this way.... You can get a 1tb portable drive for around 60-70 bucks right now. If you stop using it on the wii, it'll work on the Wii U, the Xbox One, the PS4, or your mame cab.