Notlist3d,
Im not completely sure I get your math. I did reinvest 50/50 in TH on S7 and S9 a couple of month ago with a powerprice of $ 0,055 and with a forecast saying very small diff increases for at least the next 6 month time. For now the investment calculation looks spot on.
So with a price of 0.10$ with an S7 price of 365,-$, the S7 looks like a pretty decent investment.
The key thing there is "a couple month ago" as this would be before having. And there is HUGE difference on before and after having as far as mining gear goes. A S7 pre having yes was good at 10 cent's, but post having it changed to where at 10 I would not buy a S7. So I'm not sure where you find difference in math on running a s7.
Just look at running cost at current BTC value. Running 4.73T even if you get " Power Consumption: 1293W + 10% (at the wall, with APW3, 93% efficiency, 25C ambient temp)" I just don't see as profitable currently. If BTC takes a huge jump up could that change yes. But as of right now 10 cent's I think S9 is onlly thing that makes sense again currently.
And again to be clear we are talking about now (current), not a couple month's ago.