Something else to keep in mind, is that the local-user/ap databases are master only, so if you're making use of these, the local might run in a reduced service state during failover (i.e. certain configurations wouldn't work fully). Examples are...
1. If you're using machine-auth enforcement.
2. Using the local databases for guest or RAP authentication.
I did have it in my mind a new feature was mentioned regarding syncing local databases from masters to locals, but maybe I imagined/dreamt it?!?!
Thanks.