Not an OP but I have similar experience with ZFS. Over 22 years of maintaining servers, I have had serious issues exclusively with ZFS.
My pool is there, but it doesnt want to mount no matter what amount of IRC/reddit/SO/general googling I apply to try and help it boot.
After it happened for the second time, I removed ZFS from the list of technologies I want to work with (I still have to, due to Proxmox, but without being fascinated).
I've been working with systems for a long time, too. I've screwed things up.
I once somehow decided that using an a.out kernel would be a good match for a Slackware diskset that used elf binaries. (It didn't go well.)
In terms of filesystems: I've had issues with FAT, FAT32, HPFS, NTFS, EXT2, ReiserFS, EXT3, UFS, EXT4, and exFAT. Most of those filesystems are very old now, but some of of these issues have trashed parts of systems beyond comprehension and those issues are part of my background in life whether I like it or not.
I've also had issues with ZFS. I've only been using ZFS in any form at all for about 9 years so far, but in that time I've always able to wrest the system back into order even on the seemingly most-unlikely, least-resilient, garbage-tier hardware -- including after experiencing unlikely problems that I introduced myself by dicking around with stuff in unusual ways.
Can you elaborate upon the two particular unrecoverable issues you experienced?
(And yeah, Google is/was/has been poisoned for a long time as it relates to ZFS. There was a very long streak of people proffering bad mojo about ZFS under an air of presumed authority, and this hasn't been helpful to anyone. The sheer perversity of the popular myths that have popularly surrounded ZFS are profoundly bizarre, and do not help with finding actual solutions to real-world problems.
> Over 22 years of maintaining servers, I have had serious issues exclusively with ZFS.
I've been using ZFS since it initially debuted in Solaris 10 6/06 (also: zones and DTrace), before then using it on FreeBSD and Linux, and I've never had issues with it. ¯\_(ツ)_/¯
Not to be deliberately argumentative but still no concrete examples of zfs failures are shown, just hand wavey "I had issues I couldn't google my way out of". I've never heard of a healthy pool not mounting and I've never heard of a pool being unhealthy without a hardware failure of some sort. To the contrary, zfs has perfectly preserved my bytes for over a decade now in the face of shit failing hardware, from memory that throws errors when clocked faster than stock JEDEC speeds to brand new hard drives that just return garbage after reporting successful writes.
