DVD+R DL works with modchips, I don't think it works very well with softmods. My Wii won't read dual layer discs reliably anymore, a lot of legit users had this problem when Smash Bros first came out so it's not exactly uncommon. People had to send their Wiis in to Nintendo to get the laser "cleaned"
Kirby Wii has some weird anti-piracy checks AFAIK.
USB loaders are the way to go nowadays anyway.
Kirby's problem is pretty strange.
It is the only game I know that gives me a disc error on the home menu instead of after loading the game.
