This is very much our experience as well. As complexity increases, the marginal utility goes down, as operating concerns skyrocket. You really need pretty spec

This is very much our experience as well. As complexity increases, the marginal utility goes down, as operating concerns skyrocket. You really need pretty special operational needs to run multi master relational databases. It is am engineering tradeoff between complexity and fragility. In our case Galera / PXC ended up with a significantly worse availability record than running our previous simple master slave failover system. See my other comment for more details.