Let me add my two cents to handling of planned downtime: This month, my ISP has been announcing already a second emergency downtime of their infrastructure. An emergency one, yet planned, required to replace some backbone equipment I guess. In both cases they reserved 3-hour windows, but the actual outage of connectivity can be much shorter than this. It would really be beneficial to be able to specify planned windows for maintenance, which does not necessarily mean the node would be off-line for the whole time, but the network should expect legitimate unavailability of that node and, e.g. postpone any writes to it.