Meanwhile the latest S9v1 statistics on the pool since the S9 existed:
They've found 82 Blocks, but expected to have found (BDR) 110.666 ...
28.666 ... of all 37 "short"?
We're back on the whole "the S9s are the entire reason for our bad luck" thing again? 
Edit: for the record, a 12.9TH S9 @ 1509 watts (1372+10%) hitting only 74% expected is still cheaper to run than 6TH @ 1000 watts hitting 100% expected - by about 8 watts per effective TH... let alone the fact that 9.5 > 6