A very simple solution is using robocopy.exe, it comes with your windows installation:
robocopy.exe /MIR /NP /NJH /NJS /NDL /R:0 /W:0
It's the foundation of what I use to backup all the machines around. If you have filesharing enabled (admin-shares even better) and an admin-user which has the same password on all machines.. it's very straightforward to sync things around, no need for single shared folders.
robocopy.exe \MachineA\d$ \MachineB\d$\MachineA_DriveD ..
This syncs D:\ from MachineA to D:\MachineA_DriveD on MachineB, whether its LAN or WIFI and folder datetstamps will be preserved as well. o)
I looked into SyncBack very deeply and even purchased the Pro version. I did that because of good reviews and the promoted scripting api. It did not work out for me, the scripting api is horrible and even though there are a ton of options, I couldn't get along with it. This SyncBack-Touch thing on my Android also did not work as expected. Just my 2 cents on this one.
I reverted to a scripted little framework and robocopy.exe, much simpler and easier to customize the processes with these basic tools and I still don't have to miss advanced features like WakeOnLAN, EMail-Log, Auto-Shutdown, Quotas, File-Integrity-Checks etc. I'm happy to share it with you, it's text-editor configuration only, but you can see that as an advantage as well.