USE=-native-symlinks (https://wiki.gentoo.org/wiki/Project:Toolchain/use_native_symlinks) provides a way to hide unqualified tools from toolchain to ease detection of hardcoded tools.
It is still useful to have an easy way to run './configure && make' as a user when developing local projects.
PATH="$(gcc-config -B):$PATH" has a few limitations:
- it lacks certain links, like /usr/bin/cc (bug #713214).
- it does not update automatically for current processes when gcc-config swiitches to another profile.
In this bug gcc-config and binutils-config can maintain complete set of symlinks to have native toolchain working that can be usable in PATH.
CCACHE story around those paths TBD.