I have over 100 T9s running with zero failures so far. They clown on the S9 for reliability. IMO the efficiency trade-off is well worth it since its likely an S9 wont run problem free until you reach ROI and it looks like these T9s will.
I wonder whether the efficiency trade-off translates into selling used equipment from their own mine. The second hand equipment they gave me in replacement of my faulty boards was definitely from their mine, but I wonder if they are selling second hand machines as new.
How long until you reach your ROI do you think? And how long have you been running your T9's?