Using rsync to sync between 2 Macs wirelessly
Even though I can tell, that this is a bad idea, here is my answer :

If you have a router in between, that should work, if not, you need to setup an Ad-Hoc network.

Set-Up a ssh-keypair :


  ssh-keygen -t rsa 
  ssh-copy-id 'user@otherMac'


And write your rsync for each mac :


  rsync -e "ssh" -rc --delete ~/ user@otherMac


(-e "ssh" = use ssh for transfer 
-r = recursive 
-c = compressed 
--delete = delete files that are not on the local device
~/ = Home-Folder )

U can, of course, adjust those.

If you don't have static IPs on the Macs, I guess you can call them by their DNS-Name, like "Toms-MacBook.local" or you can ping the DNS-Name and output the IP and give it to the rsync command.

And the delete option is the problem. If two macs are working at the same time, files are deleted when you are working. In such cases you would use a server.

In the end, you have to try it out and decide for yourself, if there is nothing to lose, I would also give it a try.