Running ZFS (FreeNAS/TrueNAS) on 2 home made NAS devices for years and years, I can say it is rock solid without ever using ECC RAM due to lack of choices. I can bet there were many soft-errors in all these years, but so far I never had problems that could not be recovered; the biggest issue ever was destroying the boot USB storage in months, but that was partially solved lately, I moved to fixed drives as boot drive and later I moved to virtualization for boot disk and OS, so the problem completely went away.

occasionally a bit flip will corrupt the state of something important and long running, a reboot will obviously clear this

usually it will hit nothing and have no side effects