Wii homebrew is ran through HBC on vWii, just like on the regular Wii.
I'm pretty sure there shouldn't be any disadvantages with running USB loaders or Nintendont on a Wii U.
Also I don't know if there are any performance improvements with running emulators on vWii compared to a regular Wii...
Downloaded it one day, made like two, then never used and eventually uninstalled.
Basically, I don't give a shit about it and it's kinda annoying when other people bring it up.