I now have 19 s9 and still have had no problems. I must be the the luckiest guy in the world. ....
What batch? post again in 6-12 months.
As I have A6, S7, A721 and S9 I can comment very well on durability and customer service

S9s are a steaming pile of bullshit, but the cost less to run (in the long run [100+ blocks]) than A7s, and therefore have a better ROI... It's that simple!
You ignore that the S9 seems to have a higher failure rate
But yes...back on topic: kano.is pool
Batch 5,10,18,22,24.