I’m a little confused by your post. One on hand you’re saying you don’t need to use ECC to run FreeNAS but on the other hand you tout all the file integrity features of ZFS. You can’t have it both ways.
Hopefully this clears it up: With ECC memory, ZFS provides greater integrity guarantees that other storage systems. Without ECC, the guarantees degrade to no worse that the said other systems. My touting of the integrity features are when you elect to use ECC memory in order to get those guarantees.
I can’t think of a single benefit ZFS has over NSA’s for media storage without ECC.
There’s a long list of filesystem level features which are available in ZFS (or shared with very few other filesystems). Only the greater integrity guarantees are reliant on ECC memory; the filesystem features are available both with and without ECC. Also, several years ago I was running ZFS on a non-ECC machine and it survived an odd drive failure that other systems at the time would not have survived and many still wouldn’t today. This is one of the reasons why integrity is so important to me today.
I could go on, but this thread would be at risk of devolving into a ZFS vs NSA debate so I’ll just leave it with the above.