I actually made an installation script the second time I installed gentoo. Now, I just have to move my already config and that's it. Seriously, that's not that hard.
You just have to copy your config file, and make olddefconfig; make modules_prepare; make; make modules_install; make install; grub-mkconfig -O /boot/grub/grub.cfg I don't even know if "make modules_prepare/install" is any useful. And people bitching about configuration; seriously, I had to move everything to each new distro I ever installed. The only difference with gentoo is the installation; even though you can automate it with a script.