I can definitely confirm your question. We had a battery fire and the engine stopped. The setup has 2 ignition systems available so I am recommending a switchable 2 battery system.
My question would be, how is the shortcoming in system design being introduced? I think the electrical schematics at viking include a backup. Is the basic CH-XXX wiring system being used with an EFI/elec ignition installation?
There is a trend happening here. Not enough awareness of additional redundancy needed for elec dependent engines.