The Unigine Heaven Demo is unique in that it is the only demo which allows for the following components in one package.
The ability to compare DX9, DX10 and DX11 in the same environment allows for the unique ability to see how the different cards perform across these different comparable environments. Tessellation was set at Normal Mode.
The updated 2nd version of the Heaven demo offers more segments and more options. DX9 and DX10 runs are no match for any single 6800 or 6900 series card, with only the single 6800 series falling below 60fps. The DX11 run in more demanding in a single widescreen, requiring a 6900 series in CFX to pass 60fps (and pass it by a good margin). Single 6900 series cards also pass 30fps at either 1600x900 or 1920x1080.
Eyefinity is an obvious strain on any configuration. A 2GB card is required for Eyefinity in DX10 or DX11. No combination of cards will hit 60fps in DX9, though the high end configurations come close.
The HD 6790 will hit 30fps in single screen configurations, though Eyefinity brings a serious blow to performance. With quality reductions you could hit "playable" framerates in Eyefinity.
The Heaven v2 Demo continues to be a powerhouse in bringing graphics cards to their knees.