FYI: if you want to edit this into you post:
s9i uses 1320 +10% according to the specs on bitmain's site. So we have 1452w for 14th/s which is 103.71w per TH/s.
So the math goes like this:
((103.71-81.25)/103.71)*100= 21.66% more efficient.
Not bad for the first miner they ever released.
Thanks. Will add to post but this 10% oscillation in power usage can be added to both miners.