Best choice for the future & ARMA III

So, I almost had a GTX 680 snagged for 300$. But the guy gave it to his brother, slightly pissed now, but faced with yet another problem, and I need help from my fellow graphic card experts around.
So we all saw the potential from the 680, and especially the pricing, real nice from Nvidia! Anyway that is not my problem. I am stuck now between either buying the GTX 680 for 620$ (388£) and the Sapphire 7950 OC for 490$ (308£), and crank OC's up on the 7950 ofcourse. I will also only be gaming on one 1920x1080, hence thinking the 680 might be a bit overkill...
The two cards:

7950: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
GTX 680: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

My main concerns are two things:
1. I will need this card to last me for AT LEAST 2 years on.
2. I want to be able to play ARMA III on at least high (not maxed) with decent framerates.

So what is the verdict gentlemen? Do I pay the extra 130$ or shall I just go with the 7950 and overclock the crap out of it?