there are a plethora of bugs around RAID5/6 that makes it straight up unsuitable

btrfs device add /dev/sdb /mnt

overview and benchmarks

“Authority” in this case doesn’t get much better than Matthew Ahrens, one of the cofounders of ZFS at Sun Microsystems and current ZFS developer at Delphix. In the comments to one of my filesystem articles on Ars Technica, Matthew said “There’s nothing special about ZFS that requires/encourages the use of ECC RAM more so than any other filesystem.”