`nvm install v4.0.0` and you're ready to go.
nvm install node --reinstall-packages-from=nodeEverything else is done over Github's super-secure HTTPS - so there's really nothing to be paranoid about.
> nvm install stable
v4.0.0 is already installed.
Now using node v4.0.0 (npm v2.14.2)All node versions are now stable, and version numbers now communicate breakage, not stability. As it should be.