Think about this point though, here is what AMD is basically currently saying - in our forum member's point of view - "To get our cards to run at an acceptable level, you must install radeonpro and tweak/apply different settings, vsync or whatever it may be". Does that not sound wrong to you? SLI works very well right out of the box, as it is intended to.
I just have a problem with people recommending crossfire at this time when SLI is clearly the better option, that's all. 650ti Boost, 660, 660 ti, and 670, perform very well in SLI for the money. Price/Performance is what it is all about, isn't it ? Look into 650ti B and 660 for 1080p gaming.
BTW i'm actually really excited for this game and quite happy NV locked this in. Not for bundling, because i could care less but it will surely be optimized very well at launch and additional features from physx are always welcome