I recently obtained a better component capture card and wanted to test it out. So, here's Wii Component video compared to GameCube component video.

The first clip is the Wii with Corneria playing. The second clip is the GameCube with Star Wolf playing.

Yes, I used homebrew to load a backup (I ripped) of my legal copy of Super Smash Bros. Melee. AFAIK I didn't fiddle with the video settings in either homebrew method. I then used an Elgato Game Capture HD to record the footage at 640x480, placed the clips side by side and uploaded the footage. If it's that important, I used a USB 2.0 mini-usb cable.

See the results for yourself.