Advice on backup and replication

Personally I haven't seen enough reliability and consistent performance out of ReadyCloud to recommend it for corporate use. If the two sites are seamlessly connected by the routers using VPN tunnels or perhaps MPLS, then backups can run over the existing corporate network. If they aren't connected that way, the I'd suggest creating a corporate network as part of this project.

The continuous protection offered by snapshots are useful locally on each NAS, but you can't back up the snapshots to a remote system efficiently. The built-in NAS backup jobs do simple file copies - they aren't capable of 2-way sync, and there isn't any versioning. I'm not a replicate user, so I don't have any feedback on that to offer. Egynte is a Netgear partner, and you might want to look at their ReadyNAS offerings.

The net here is that (a) CoW Snapshots are useful, but you need to understand their limitations (b) you'll need to make a deeper dive on the Netgear backup facilities to make sure they meet your requirements.