And I said I will buy one and test. Its all speculation at this point. Also it greatly depends on the algo. Why are you all so hung on ethash that is about do die anyway. All will either fork away or perish under ASICs. So comparing ethash is poor comparison. New algos are comming out like coocko, ProgPow and others and there the difference is more then just 2x I would bet. Even current Vegas outperform 570 more then 2x. Also 4GB cards already can't handle some of the new algos.
Mining ETH for profit is a thing of the past.