Nope. By the time you find a game/setting/resolution that causes a performance hit due to vram capacity at the 2GB mark, the 670 (and even 670 SLI) is out of power and you need to turn settings down, making the vram issue meaningless.
Now 670 SLI is borderline enough that there may be merit to buying a pair of 4GB cards instead of 2GB ones, but there has been zero practical benefit shown to a 4GB 670/680 over the 2GB counterpart, up to and including 7680*4800 resolution.