I'm not fully knowledgeable with how the Wii U homebrew is now with all the recent changes but I do recall that once its formatted on the Wii U end it makes it pretty much encrypted and unreadable on PC or any other device. It would be cool if you could have both Wii U games, Wii, and Gamecube all on one HDD but it pretty much sounds like the HDD would be dedicated to solely Wii U games thanks to the way it formats the drive.