HD5870 + 5850 Crossfire to a GTX670

I read a lot about these Graphic cards and numerous sites point out that the 5870 crossfire is faster then the 670. But other forums say its worth getting the GTX670 over then 5870 crossfire, Leaves me confused.

So If the GTX670 worth it over high overclocked 5870's?

I'll be getting an EVGA GTX670 for free, I recently had a 5850 go bad and I picked up an 5870 for $30 USD with bad fan, replaced it and its no much smoother when I had 2x 5850's, making me think it was going bad for awhile.

I do not care much about power draw, I know the GTX670 will use less power, im not looking at that, Im looking at performance. I know I can SLI, But It will not be an option for some time.

I do have a fair bit of driver issues with these cards, but after so long with these cards, I know all the work arounds. Other then the 14.4 driver USB Filter drivers causing random lockups.

I know that the GTX670 will OC to GTX680 levels pretty easy. So does anyone know if its worth it? Will I see a performance difference if say Crossfire did work properly.

I know the 1Gb frame buffer hurts me in BF4, but I can still run high with over 60FPS.

Thanks
-Viking2121-