This idea seems to be profitable for Gentoo users. I've sometime thought about it.
Should it be done or not, let me share my thoughts of main disadvantages for Sabayon I can think of, for fruitful discussion. - A git repository created from scratch wouldn't have ebuilds etc. history (logs). But if for example the "Gentooish" overlay is made of current sabayon overlay from which Sabayon stuff is removed, git history of deleted files would be still available in it. I don't know if that could be made better, but if not, maybe this problem could be ignored (of course if answer for this proposal is "yes"). I can only think of spliting the overlay *not* into two physical git repositories, but into two branches. Question here: would it be a comfortable solution for the maintainers - hmm, it could work. But I'm not that sure layman-and-others support it. - It's possible some eclasses and/or virtuals would need to be shared and maintained simultaneously in the two overlays, but it's IMO no big thing. I don't know how it looks from the perspective of the infrastructure, so I won't say anything in this regard. On the other hand: what good could it bring to Sabayon - more fame. :)