With your current ebuild you might expect problems running 32bit apps, that use opengl, for example, if you run a game with wine.
Then you sort of did what sabayon people did.
about the distro thing: sabayon isn't the gentoo distributor. is an overlay and a sabayon distributor. so if you want a distributor for gentoo use the gentoo base repo. that's why i don't relay much on sbayon stuff. some things compile and work, some others do not. i personally like to use xeffects, gentoo and at last if none of the gentoo,xeffects compile and work the sabayon ebuilds.
as for the soname, i've said that i think ati would correct the issue in the next release, since now it's out. in the meantime, let's hack the ebuild and have the driver installed....