ZFS does nothing to protect you against RAM corrupting your data before ZFS sees it. All you'll end up with is a valid checksum of the now bad data.
You can Google more, but, I'll just leave this from the first page of the openZFS manual:
Misinformation has been circulated that ZFS data integrity features are somehow worse than those of other filesystems when ECC RAM is not used. This is not the case: all software needs ECC RAM for reliable operation and ZFS is no different from any other filesystem in that regard.[1]
One snapshot would help because, if EVERYTHING collapses, and you need data recovery, the snapshot provides a basepoint for the recovery. This should allow better recovery of metadata. Not that this should EVER happen -- it is just a good idea. I use Jim Salter's syncoid/sanoid to make snapshots, age them out, and send data to another pool.
I agree that ECC is a damn good idea - I use it on my home server. But, my lappy (i5 thinkpad) doesn't have it.
