Upgrade to a 680?

I currently have two GTX 460se 1GB cards in SLI (overclocked as well) and was wondering if an upgrade to one GTX 680 would provide a decent improvement on performance. Right now they can pull a mix of high and ultra at 1080p on Battlefield 3, but I want to shoot for all ultra and be a little future proof. So what do you guys think? Upgrade or wait a while? If I did buy a GTX 680, it would be a non-reference one, which means I'll be waiting a little while to upgrade. I do want to get away from SLI too, that is one of my reasons for upgrading. Games like RAGE make me really regret having SLI because of how poorly it performs with multiple cards.

I have an 850 watt corsair psu, so power is no issue and my cpu is an i5 2500k @ 4.5 ghz. I do not have a pci-e 3.0 mobo but that really shouldnt make a huge difference should it?

Any opinions would be appreciated. Thanks.