I am using latest beta drivers(Catalyst 13.11 beta v8) running on Windows 8 64-bit, and I get the error saying OpenGL performance counters are not available for this hardware both on gDEBugger and latest GPU Perfstudio, when profiling an OpenGL 3.2 program.
I can access D3D11 performance counters without any problem.
Hopefully AMD will include a fix in the next driver.