Re: [ANN] Spondoolies-Tech - carrier grade, data center ready mining rigs
but looks liek I have ot settle for some Antminer S7's instead. 
No, you don't have to settle for an S7. Do the math. You are unlikely to ROI before the block halving. Better off buying BTC and hodling while it's 1BTC < $250 USD, IMO.+1
Bitmain and some customers calculate ROI with suggestion the difficulty will not change
https://bitcoinwisdom.com/bitcoin/difficulty
heh with the current difficulty rise likely due to KNC bringing up its 16nm chip run for their large world class data hall in iceland and bitfury going to do the same in probably
2-3 months in that they've taped out their 16nm stuff...this 5% diff rise could be a pretty good constant for the next 4-6 months ....trying not to be dramatic ..but it
kinda looks ugly if my guess above is right
The ones that calculate with no change are dreaming. Some claim when new gear goes online old gear is going offline. But I have found old gear normally does not go offline but to a cheaper electricity area.
This week I think a min of 5. But guess we will see. We are going to have a few pumping out gear though.