Hi,

now I redeploy the primary (after, say, the machine goes up in
flames). For a short while there secondaries will see the dummy zone's
serial. IF I'm unlucky and the serial-math works out 

Do you think that you make 2000000000+ updates to some zone? It is 23 days of 1000 upd/sec torture.

And even if, than if you configure journal-content:all on the secondary/ies, they should have overview about all the history and don't mess up if the primary goes backwards in SOA serials.

Libor