SLI GTX670 is good performance no doubt, however its low memory bandwidth (because of its narrow 256-bit bus size) would mean you would get much greater performance hit when using settings such as SuperSampling, and playing memory intense titles such as Metro, or...any games that uses high res texture, and this apply for 1920 res, not just higher res.
If I was in your shoes, I would probably do the same in keeping the SLI GTX670, but I'd make do with not using settings like SuperSampling etc. If you not crazy about games like Metro, the SLI GTX670 would still be fine in the short term, and should last you till next gen 20nm upgrade.
512 bit bus effective though with SLI.