I have just bought an R9 270, and I am trying to get it working on Debian Wheezy alongside my 6770.
I am using the latest 13.11 Beta drivers.
The output of lspci is:01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Juniper XT [AMD Radeon HD 6000 Series] 02:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Device 6811
And fglrxinfo:display: :0 screen: 0 OpenGL vendor string: Advanced Micro Devices, Inc. OpenGL renderer string: AMD Radeon HD 6700 Series OpenGL version string: 4.3.12614 Compatibility Profile Context 13.25.18
Also, my second monitor on the 6770 is buggy (doesn't render windows properly) on Gnome 3.
Has anyone had any luck with this?