My good sir, you may be misinformed about Project: M. If ya believe it requires modding or hacks in order to play, that's not the case. All that's required is an SD card and Brawl itself. No homebrew, no modifications, nothing that posses any risk to your Wii (U). P:M is perfectly safe. I wouldn't be playing Project: M myself if there was any possibility of damage, as I'm not stupid enough to put my year-old Wii U at risk.
... Well, if you have an NTSC console.