CyanoticBrute :
Eventually i will be doing 2 or mabye even 4 way sli with 680's.
Before you get to that, "son of kepler" GTX780 will launch and 2/4 way sli GTX680 will not be a good option.
Graphics card designers know very well how to balance the specs for optimal effect. Today, the amount of vram supplied with each card is appropriate to it's capabilities.
The 4gb spec is largely a marketing response and product differentiation.
The benchmarks I linked to seem to show little benefit of 4gb, even with triple monitors.
In some cases, the 4gb cards did slightly worse.
No doubt, there might be some situations where 4gb is helpful, but is it worth the extra cost/
If money is no object, and you are thinking about quad sli gtx680, why not buy a top GTX680 with 4gb in the first place. Cost be dammned, buy the best you can afford.