The whole point of the ZFS needs ECC statement is that it holds true even for non-significant deployments. Such as a home-NAS. And at that scale it comes with a quite significant cost increase. Rather than reusing your old workstation you need a new server class machine with lots of RAM, even though the CPU requirements aren't that high.

If your backend is a zvol you get the integrity advantages and cheap snapshots regardless of your VM filesystem, so it isn't really a fair comparison with an "EXT all the way" scenario.