I've flown Noumea, Vanuatu, Nadi, NZ & YBBB/YMMM in a DA42-VI w/satphone only - works fine. You don't need to worry about HF or CPDLC. If you're going further out to Tahiti, Oakland etc, HF is mandatory, but a DA42/62 is not really the right plane for regular flights between those areas anyway -...