LDSman 
Personally I don't think the gamecube is worth modding now not when the Wii is so easy to mod to play GameCube backups (If the version of the Wii has GC ports and to play from DVD+R be one of the first few released) & Wii (again needs to be an older version to play from disc) and emulate tons of other systems including GBA
You can still play everything from the newer Wii's with GC ports also but you do need a USB HDD to do so that would obviously cost
Games from DVD+R/-R read apx half the speed of retail discs that can be noticable in games that will lag for FMV when ran from duplicated discs
From USB HDD (not to be confused with a USB stick that still has issues)
Wii games tend to run better from HDD and gets read faster than retail disc so faster load times ect
GC games also run better from HDD but the method lacks some sound support (only for a small number of games about 10 I think it was)
WiiWare just runs as it should, but faster read times again than real Nand (A virtual nand is created) plus the added bonus of escaping from the limited space the internal Nand has
VCWare... same as WiiWare
Emulated games run as well as the emulators provide
Other methods can use the SD card but again will be slower than retail discs and slower than internal Nand for WiiWare, WiiWare on SD is officially supported but it sucks to be honest and is too slow for a lot of WiiWare and VC games
Overall it is more hassle free to use a USB drive, plus there are some cool things you can do as an added bonus
My fav console that is modded is possibly the original XBOX but I did install a new large sized HDD, but that plays a lot of emulators as well as Xbox games (I can't stand the xbox controller though so I use a PS2/PSX to Xbox converter for my controller, I have 2 of those)
]
