Phoronix: AtomBIOS Radeon vs. RadeonHD Drivers?

After a Linux user had read about the open-source RS690 3D support found in the Radeon driver (xf86-video-ati), he had asked on the RadeonHD mailing list what are the differences between these two open-source ATI/AMD drivers. This has led to messages from both sides and implications that the Radeon driver is cutting corners and little to no cooperation between the two driver teams at this point...

http://www.phoronix.com/vr.php?view=NjMwOA