It's a gamble. I think the quality control just wasn't good enough for all these 17 series miners to get a reliably good product, but it seems like some batches were fine, others were horrible. I have 10 S17s that came directly from Bitmain in one batch and haven't had a single one go down. Been running for nearly 2 years. Got 7 s17 pros in another batch from Malaysia and had issues with 3 out of 7 in under a year.

So could go either way. With used miners, if they've been solidly running with no issues they may be good and the original owners were the ones that took the risk. Or it could be every single miner they are selling had issues and it's just a matter of time before they start failing.

I'd just go into it assuming 25% of the hashboards will die. Make sure the #s make sense with that assumption. Consolidate working hashboards into fully working miners and either sell the bad boards for parts or see if you can find a repair shop.