Interesting. Do you have any way of checking that the change has actually propagated through the system before starting to act on it? Is the system consistent at all times?

If I understand correctly, the client can connect to any instance and its request will get routed appropriately. Let's assume that you take a master offline and promote one of the replicas to be a new master. Won't that lead to a window in which (from the point of view of different instances) there are two masters at the same time and some writes are sent to the wrong instance?

EDIT:

One solution for such things is to use something like Zookeeper (or some other system whose documentation mentions "Paxos" ;)). Have you considered that? How does what you are doing compare with that?