Very true. ZFS was not extensively covered, or hardly covered at all. I have put emphasis on Ceph purely because I know it well enough and have built several Proxmox clusters on it. I live, breath in Ceph as you do in ZFSBut first impression: I am bit disappointed over the extend of ZFS;-) For SMB's which don't have money or space for a storage cluster a unified storage server based on ZFS is definitely the answer IMHO. Either Nexenta or, to my taste, Omnios. If a HA storage cluster is a requirement later on Nexenta has built-in support for clustering and clustering can be bought as an add-on for Omnios. So ZFS can scale as well. In my book ZFS shines above all other filesystems, both in performance and in stability and security.
I will always remember your contribution during my journey of "getting to know Proxmox" many months ago. You introduced me to OmniOS which allowed me to really use ZFS. But fell in love at first sight with Ceph later on. To me Ceph just seems much easier to work with even with low budget SMBs without much complication. HA works out of the box without paying anything.
May be future book collaboration with you on Proxmox+ZFS is a possibility.