just upgraded to xorg-1.11.3 running latest nvidia-drivers-290.10#3.2.0-sabayon
I have a nvidia-Geforce 7300GT, (which doesn't appear to be a legacy card, according to the list)http://www.nvidia.com/object/IO_32667.html
and everything works perfectly.
full 3D acceleration, compiz, so for me there's no need for xf86-video-nouveau drivers
didn't got a chance to test it on a legacy card, since this is the only card i have....