This forum covers all Gentoo-related software not officially supported by Gentoo. Ebuilds/software posted here might harm the health and stability of your system(s), and are not supported by Gentoo developers. Bugs/errors caused by ebuilds from overlays.gentoo.org are covered by this forum, too.
but the idea is good - it would be nice to be able to select compiler with paludis or even with portage (I know about scripts but it would be nice to have it as build-in)