I don't think you understood the question. I have a farm with 79 Terrahashs of Bitmain and Avalon equipment. I wanted to
know if anyone, off the top of their head, has done the calculations for the ROI on ONLY the S4 based on rumored price
and the crap performance of the coins value over the last month (and of course taking into consideration the difficulty swings).
There are too many conflicting stories out there from people that don't have a clue about much else than sitting at home with
their three S1's just "burn'n up" the pool they're in and thinking they have all the answers. (I haven't even met people with
more than I have with all the answers!)
Too much speculation at this point. The currently low exchange rate and the rapidly increasing network difficulty makes ROI very difficult.
It technically makes it near impossible if you are paying for power. Especially if the 5-20% difficulty trend increases.
A single unit to ROI on its single earnings will possibly never happen.
https://bitcoinwisdom.com/bitcoin/calculatorPeople will be paying for electricity cost before earning enough profit from mining will have paid off the unit.
Of course this does not apply to people applying other earnings and profit from previous units that have already ROI. I'm simply referring to if you buy 1 antminer s3 today, in about 3 months you'll be paying for electricity to run it out of pocket.