We are on different paths. There are clearly many ways to skin a cat ( and cat pumps). I’ve switched to the low energy one from the high pressure version. Quiet, cool and low energy. I’m also working up to ditching the genset. Noisy, hot and unreliable.
It sounds like your engine may soon to fulfil the role of genset if you were to ever need one, but I‘d be surprised if you can run your watermaker off your inverter. I can’t run my old one easily off a 5kw inverter (2.5kw motor). Start up loads are on the limit. Have you tried it?
