You are aware that Redhat (for example) has dropped support for BTRFS, and that there are some major issues with BTRFS development? Actually 80% of NAS devices specialized for video / photo are ZFS now (Lumaforge, Small Tree, etc.)
Development of ZFS-on-Linux is going very well and actually FreeBSD and ZOL will have a single shared code base:
So if Freenas is not an option, ZFS runs on linux just fine (Cent OS, Ubuntu) and it can also be used with Openmediavault (NAS appliance based on Debian).
With so many options I think that there is no reason to clone Synology and have limited resources to find a solution if something goes wrong.