Great info here! And, you may also get some further insight from a similar thread from almost a year ago.
Similar topics and methods discussed.
And, to Jim’s point about ‘pulling’ backups, instead of pushing: I certainly understand your perspective with both sides being both primary and backup, but you can setup permissions on these datasets to limit your risk should one side be compromised in some way. Datasets can be secured, and the sync users can also have their access limited. It’s just a question of how much risk you think there is, and how far you want to go to be safe. If you have just these two copies of your data, and you value that data, it may be worth considering.