yep, but at least:
"After months of testing and a lot of headache, our official recommendation to users about adopting SLI/Crossfire for ROF remains the same. Our engine was not designed for it and implementing it was very difficult and as I mention above the results are somewhat mixed. We still recommend that you invest in a really strong single card solution to boost your ROF frame rate if you feel it necessary. We suggest you save the money you would spend on a second video card and use it to buy a better processor if need be
http://riseofflight.com/Forum/viewtopic.php?t=20189