We have T17s from late 2019. unreliable and a continual headache.

1) 30% of total hash boards now dead.
2) common temperature sensor failure causes machine to stop hashing
3) if u lose a single asic chip, your board is dead (previous gen, s9 will keep running with less)
4) There is a design flaw where left most board lower corner chip has very little airflow, and since each chip has an individual heatsink... that one corner chip will end up frying, its almost inevitable.

I would only consider them if I had the resources to tackle the failures... Im guessing u have really cheap electricity too?