Oh my god I fixed it!
I disabled my 4th GPU, a GTS450 that I use as physX and for a 4th display when I'm in productivity mode...
Anyhow, device manager disabling that card stopped the flicker with SLI and the motion blur is no longer glitched.
Hope this helps!
So that fixed the main problem with the flicker and the motion-blur, but there are issues remaining in performance. Most times I get 90-120 FPS in the game. But when I look at certain light-sources the game chugs down to 1/2 of that and the mouse starts lagging with what feels like at least 500ms latency on the response. It jumps right back up to 120 FPS and no mouse lag once I look away.
Here's a Spot with one of these lagging light sources.
http://cloud.steampowered.com/ugc/594681848097286970/FDFE9C809E8A4DB966A8FD38A44B9FEA87DFD63B/
And here's what my GPU usage is like when looking at it. The dips in Low GPU/Low FPS are when I look towards that light and the High points are when I look away.
Before this area SLI seems to have been working well, looking like this.