I have looked at this unit. It's well made and runs quietly. However, the Stirling cycle converts most of the energy in the diesel to heat and a relatively small amount goes to electricity.
If you have a big need for hot water and/or cabin heating and can handle only 800W of charging capacity, it's OK. If, like me, you live in the tropics, you'd be better off with an AC generator running through an inverter and I'd recommend a Whisper 3.5kW from Mastervolt.
The Whispergen unit retails for NZD19,000 approx.