you are being very helpful, thank you! However, what (patched) portage driver are you referring to now? 13.1 or 13.1_pre897? The first seems to be for the "newer" radeons (this info is also contained in the ebuild), so consequently, aticonfig --initial looks for compatible adapters and finds none (since my card is r600). I emerged it, but then unemerged it.
The "pre897" legacy version of 13.1 is supposed to be for r600 etc., but it doesn't seem to be patched for Xorg >1.12, because it wants to downgrade Xorg to 1.12. This one, I didn't emerge, because I don't want to downgrade (yet).
So, presently, there is no working legacy driver (i.e. working with newest X etc.), neither in portage nor entropy?