2 zfs has pretty fast (zfs set dedup=edonr,verify) block level duplication where block size is 1MB (zfs set blocksize=1M).
3 in reality I tried to achieve proper data structure but it was way too time consuming so I couldn’t do any work other than that, thus I established zfs as a history backtrack where I can rollback to something very important what I accidentally can delete, thus using ZFS and all aforementioned its benefits