Thanks.
Tbh 4gb is more than enough for me at my res so to SLI would be way over the top and wasted.
Depends on the games you/friends play and from the many reviews I'm now a bit sick of reading, it is after all a lot of money for 4GB and a very desirable one where most complain at 2GB being only just enough. Until the reviews are finally out, I hope they cover custom AA/AF levels to utilise the additional VRAM on single displays as a direct comparison to the 2GB edition.
Performance wise on the AAA+ games - I'm thinking Batman:AC 1080p (yip, only single display) - that is badly coded in my opinion on PC (much like console-ported GTAIV), that performance-sapping game utilises on average only 50% each of a GTX680 in SLI with 1.2GB VRAM total used. A 2GB edition would be plenty there if weren't for the coding, or simply disable Physx. Framerate was a disappointing 61fps using maximum ingame settings, not sure on GTAIV since it's old and we've moved on but I kinda remember VRAM usage on maximum never went above 1.25GB. A single GPU would serve many well with provisions for another into 2013 in these examples
What concerns me moving into 2013 is the likes of the console-ported Crysis 2 with High Res Texture Pack, used 1.8GB VRAM, but maintains a very smooth 90-100fps, Battlefield 3 used 1.5GB with 120fps average. I've seen people post on this forum that a single 2GB GTX680 would be fine on Battlefield 3 with a few display settings turn down than maxing everything, but that defeats the purpose of paying good money to want to do just that. I'm hoping 4GB GTX680 will go some-way to achieving this otherwise it's just asking for an EK block.