I want to be able to drive to monitors from the CPU graphics core through a hybrid scheme, where the monitors stay attached to my primary HD6950 2GB, but the card team completely spins down until needed for a game
That's not possible. Think about it. If the monitors are attached to your video cards, then your video cards can't be completely "spun down" -- the display circuitry has to remain powered up to drive the signals to the monitors and the GPU has to be handling the framebuffer (the IGP can be handling all the desktop display tasks and doing all the rendering in system memory, but the GPU has to be pulling that into the display buffer on the card so it can get output to the screens). It's pretty minimal work but it is work and requires the GPU to remain powered up. The only way you can have "the card team completely spin down" is if you do it the other way, with your screens being driven from the video outputs on the motherboard. Then the graphics cards can go to sleep when you're at the desktop, but wake up and render for games (copying the screenbuffer to system memory so that the IGP can then display it -- which is a bit of a performance hit, but perhaps not as much as you might fear. Though as you can see, you really have to choose between optimal power efficiency or optimal graphics performance).
With the latest (1.0.105) version of the Virtu software, as I understand it (haven't actually used it), you can now hook the monitors up to the cards as you'd prefer, with the IGP getting "virutalized" so its functionality (QuickSync in particular) is still available to the system while gaming performance is maximized; previously the only option was to have the monitors hooked to the IGP with the discrete GPU(s) virtualized, for maximum power savings but a hit to performance (and possibly compatibility, since there were reports that some games didn't like "virtualized" GPUs).