Well, I also spent half of the afternoon trying to iron out issues after upgrading from 9.10.2-U2 -> Coral. First, my zfs pool was not imported (it is not encrypted), I managed to import it manually. Then, I could not modify some of the services I have installed (change ssh to allow root login), half of my user accounts were gone, no iSCSI, NFS, Samba shares... I have not even got as far as checking what about iohyve machines (but I think they were all down). I went back to 9.10, and I will think twice before trying the update another time.