Not sure if you have seen the same but it seems that techs who do server replacement work are using Distributed File System (DFS) to sync the file shares between two servers. This is overkill in my opinion and I recently found a simple lightweight file sync tool called Backvp2 from Switzerland. Now I setup similar shares on the new server then run this software from the new server. Configuring the target and destination are super easy and the syncing happens flawlessly. If there are issues with sync it has handy error codes that made troubleshooting file permission issues simple in a recent migration. I highly recommend it for all techs.