So let me understand this. Your data is important and you don't want even rare errors to occur, so you want ECC memory. However you use a non-journaling file system which is more likely to lose data?
And if it doesn't help, then why you decided to bring it as an argument?
NB: even if you use ZFS you still need backups.
https://en.wikipedia.org/wiki/XFS
(and I don't use XFS any more.)
It feels like arguing in bad faith. How did you arrive to the point XFS is non-journaling to begin with?