You will never get your bitcoin back if you buy one of these at this price. It isn't even close. This is for suckers or those with stolen electricity.
I would say the PACMiC and S5+ was the sucker's call. This thing is like the HA-HA afterward. I mean they, Bitmain, knew they had that S7 right around the corner. Yet they throw up the S5+ at a ~$2300 premium and at .444 j/GH. Then boom what not but a week or two later drop the S7? Dirty pool.
Not really, efficiency is factored into the price:
s5+ - $0.298/ghs
s7 - $0.375/ghs
But then factor in cost of operation over 200 days 24/7 uptime at your electrical rate.
Electrical operational costs break out as follows.
You save 20.5% on the GH/s up front cost. (your numbers) But lose 44% per GH/s on the operational cost of the unit (the S7 winning), then include difficulty explosion. Which means you're going to want to keep your operational expenses low to recover from that much longer ROI that is going to result.
2.01 years to make up the cost differential with power savings assuming equal hash rate.