Whoops, I didn't see that it has no TLER support. Yeah, mirrored isn't the way to go. Then again, since it has no TLER support, you probably shouldn't be using it in a RAID configuration, period.BS.
The URE rate is 10^14 still -> read error at least every 12TB. chances of a mirror rebuild failing are ~65%. I'd only use it in raidz2 or raidz3 for redundancy even during rebuild. My design would be 4x 11disk z3 + 1 spare in a 45drives.com chassis -> >200TiB usable with 2 parity disks per vdev (one parity disk is needed just to be able to read all that data correctly).