I think that will depend on the price that S7 will be after new technology kick in.
Its true that is very expensive, and the ROI takes months to get the money back.
But is worst case scenario , if the new technology kicks in in the next 6 months and the S7 drops price near the S5, and even that the profits drop to 50% actual earnings (90usd a month) in 5 months would be payed. and then start wining some juice (with free power).
Getting big profits only is possible if you have the wallet to buy the latest gen ASIC when he gets out (if the racio is any good) pay it in the next 2 3 months and then let it drain as much as possible. Then sell it to starter miners
