will Xfire help me?

right now i have one 6950 2gb
im thinking of getting another 1
but will it help the games i play?
playing at 2560x1440 (catleap!)

i play
world of Tanks (getting 40-60fps but sometimes drops to 15-25fps which is bad)
Starcraft (FPS seems fine)
Batman Arkham city (not playing at max settings)
Dirt 3
and more to come when i buy them!
also i mine bitcoins so anothor 6950 will add about 300mhash and for me who only makes 325 mhash so thats good upgrade!

Note im WILL not buy Nvidia!! i mine bitcoins!!!!!!!

At that resolution you will gain some FPS. I'm not sure on world of tanks (never played it), but there is some good scaling with Xfire with ATI cards and the fun of bitcoin mining will make it more worthwhile to you.