Brewology

The only piece of homebrew that I've heard of possibly messing up your Wii is an unstable release of a multiplayer asteroids game. It even says so in the description at wiibrew.org.

I've used wad installers and uninstallers and I have about 15+ different homebrew apps and games. Never had a problem and haven't heard of anything messing anything up for anyone else.

I, too, have had no issues with homebrew. Once you get past your initial nervousness, you'll be more comfortable with homebrew.