When I setup this server doing ZFS on the Linux root disk wasn't really practical (it looks like it is still a pain in the arse, though more workable). So if I wanted redundancy on my root partition, which I did of course, then using standard Linux RAID for the root partition was my only option.

I probably should have used FreeNAS, which would have made full ZFS easy. However when I was building the server FreeNAS wasn't as well suited to general server stuff as it is now (I run various VMs etc on the box).

You can all laugh when I blow away the ZFS pool accidentally...

I am looking forward to testing how easy it is to get one of my removed ZFS drives to boot on other hardware. That is after all the main reason I mirror rather than use higher RAID levels.