570 or 6950 if considering future dual.

The Sapphire 6950 2gb or the EVGA 570 are my narrowed down choices.

I have no immediate plans to add a second card for SLI/XFire, but dont want to hurt myself if that decision changes.

If I was to add a second card it would be because I've added a third monitor. Currently using two 23" IPS 1920x1080. I only game on the left one, the right is for workflow and references whilst gaming.

I'm fairly confident that I should be able to run both these monitors off one of these cards and still have excellent performance in many future games. But if I was to add a third monitor for surround/eyefinity setup, the choices become muddled.

Eyefinity seems more liked than surround, and also new benchmarks suggest the 6950 in crossfire scale better and use less power than 570 SLI.

But the 570 SLI is clearly a better single card choice.

I'm running the Seasonic X750 and overclock my 2500k to 4.5, so power consumption is definitely something to consider.

What do you think?
Should I get the 570 knowing that I don't need a third monitor and it will do what I need until PCIe 3.0 is prevalent?
Should I get the 6950 knowing that part of me secretly wants the third monitor and I would likely need to add a second card to see it fufilled.

If the third monitor is way down the line (late summer) I am better off waiting eh?
Also, is there any issue to squeezing a PCI sound card (Asus Essence Xonar ST) between two GPU cards? It's the only PCI slot the Asus P67 deluxe has open when dual-gpuing.