As long as I am running with at least 2xMSAA I have no problem with the basic driver and SLI.
With VSYNC enabled I am running at anywhere between %99 and %30 utilization of both GPUs (almost identical usage of both) depending on how much is needed to render the frames.

In my quest for optimal framerate, I have disabled Depth of Field, so I can not comment on whether that is causing issues or not, but as I wrote earlier in the thread, there seem to be issues with running SLI and no AA, at least on my setup.