You are better off using Plex in a jail and adding storage from your zpool to the jail vice using CIFS/NFS. Performance of the server will often be much improved and you prevent potential situations where there are lots of open file handles as Samba/nfsd has to use resources to track Plex going through all the directories quickly.
If you're worried about "sh*t going wrong" and your stuff being deleted, simply make the mountpoint readonly (that's what I do).
Just some free advice. ;)