Without ECC RAM it is entirely possible that upon reading a file may be marked as damaged when it is not, and it is entirely possible ZFS may write a file that has a bit flipped to disk (this one is silent and unrecoverable). While there is a chance, it is unlikely. In my case my zpool's have always given me early warning when one of my hard drives was having issues, even before SMART or anything else started showing warnings. Due to having multiple backups (desktop machine backs up to 2 different networked machines, and it is checksummed end to end) I haven't found any silent data corruption while writing data on any of my zpool's even without ECC RAM.
There is no file system that can protect against corruption if a bit is flipped in memory while reading from/writing to disk, at least with ZFS it can warn me and re-read the data from disk and give the upper layers a valid file.
Even without ECC RAM ZFS's end-to-end checksumming can help save your data and give you piece of mind that it is not silently being corrupted once it's on disk.
There is no file system that can protect against corruption if a bit is flipped in memory while reading from/writing to disk, at least with ZFS it can warn me and re-read the data from disk and give the upper layers a valid file.
Even without ECC RAM ZFS's end-to-end checksumming can help save your data and give you piece of mind that it is not silently being corrupted once it's on disk.