Radeon now works for me on a MBP 8,2 booted from efistub in Linux 3.8.x.
Can anyone else confirm this? You just need to make sure you add the PCI IDs to
the xorg for both cards. Should Xorg detect them automatically? Is this another
bug?

Thank you!

Now we just need the IGP to show something onscreen when switching to it and it
will be perfect...