We can simply use calculator to compare profitability, and can see that ROI for B2 is 100 days more than with S9i :
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That is, while efficiency of B2 is 15% more than of S9i, but high price makes it 30% less attractive for ROI.
I agree on the surface that the GMO B2 does not look as appealing, but if you run the same calculations accounting for difficulty adjustment over 2 years, the B2 is the only one that can give a RoI in 1.5yrs and remain profitable after that. Assuming a $50 internet connection monthly, a 10% rise in BTC price monthly (Only way the calculator would show either profitable) with a power cost at $0.09/kwh. It is not as straight forward as 10% price increase a month though. These new GMO miners "Should" ship in October, which I interpret as it being delivered some time around December. So with 5 Months of missing s9 profit ($410?) it would not matter longer term.
It would make sense to have hardware that will remain profitable for a longer time than hardware that in the near future will not be profitable for smaller miners like myself. Assuming it does not have 4 months of delays it makes sense over other options.
-I could easily be wrong and missing something that a more experienced miner may see.