If you suffer a lightning strike, the converters will be the least of your worries. On my boat, the only things needing 12V were a few of the smaller instruments (chart plotters, radar, etc are routinely available in 24V), the ITR diesel heater, and the engine. There are 3 DC-DC convertors, each producing 10A: one for the instruments, one to charge the engine start battery and run the engine, one to power the diesel heater. In 10 years, one of those has failed (diesel heater), not due to an internal problem but heating at the terminals which were not tight enough. One can always jump the batteries to get 12V in a pinch. The lighting, winches and windlasses, running lights, entertainment system, autopilot, MFDs, radar, communication equipment (except the VHF), pumps, charger/inverter, are all 24V.
I don't think a 24V or split system is significantly less reliable, and due to most of the currents begin cut in half it can be argued that it will be more reliable.