Waninkoko known for his WAD Installer for the Nintendo Wii, has released a new video showing that he downgraded a Wii System Menu downgraded from 3.1E to 2.1E. Nothing is special right now or anything that requires a downgrade but this video shows that it is possible and it can be done if needed.
This process seems to be very dangerous and can brick a lot of Wii's. Again, this is just a video to show that its possible but no files were released due to high risk and dangerous process.