I have tossed around the idea of upgrading to a 680 but to get the 4GB version, after I sold my 580, I'd have to drop like $250 to get one and I just don't feel like I would get $250 worth of benefits. Going from an old 24" LCD to one of the new IPS monitors... that would def be worth the $300 or so.
Any general info as to the types of games that require a lot of VRAM? I play Skyrim and Arkham City now but will be looking for some new games shortly. I tend to play RPGs mostly... looking forward to the new XCOM. Might try Badlands2 etc. I don't play many FPS except for the more adventure based ones like Fallout.
None of the games you play will require you to have more than 2GB. Maybe if you use heavy modes on Skyrim.
I currently have a 670 with 4GB but i got it to be safe. Did not mind spending few more bucks to be honest.
If you feel the same, than get the 4GB.
Do you have to? not really.
But as far as I see for you 2GB will be right.