First, I would recommend unlocking your bootloader so if you do get the BLOD you can use the fix in the thread you referenced.
Second, Keeping it stock or not really doesn't matter. What matters is keeping the heat down. What I personally do to keep the heat down is disable 2 of the big cores, underclock both little and big cores, enable vdd restriction, and don't play games or anything else that would heat the phone up for a prolonged period of time. Performance is still good while keeping the heat down at the same time.
Having said that, its still a crap shoot on whether you get it or not.
Thanks for your advice, so that's why my nexus 6P is dead again. I think I'll go with stock and keep my device's temperature as cool as possible. Does the guide on this thread (https://forum.xda-developers.com/nexus-6p/general/bootloop-death-blod-workaround-zip-t3819515) already covered all of your suggestion? what is your current setting in terms of under cloacking?