Good day! First of all, sorry for the late reply. I had to attend to a course a bit far away from home and it was pretty intense.
Now, back home, I'll try the suggestions, thanks! Just for the sake of preventing a future failure, besides personal files (minimum and obvious) the "world" file and the binary packages, built along with the package installation, what else should I backup so that I would be able to quickly restore the same full working Gentoo in a new hardware without having to work from stage3 up? The portage tree is one of those items, for sure. But what else? Thank you all and a good sunday. Francisco