I went thru the same analysis a few months ago with various suppliers before deciding to order new system with DC HP Pump as being the most dependable/versatile solution, while cruising remote
I like to make water underway but don’t like to run my starboard mounted generator while heeled
Also, I don’t like the idea putting all my eggs in one basket of depending on a 3000Watt inverter running a 1.0 HP motor
in the tropics,… as well as other AC demands that may be used (electric kettle/microwave/toaster/office stuff).
Solar, High output Main Engine
Alternator, Shaft Alternator are independent of any Gen/Invertor problems in making water with a DC system.
My only added cost of using a DC 1.0HP pump instead of AC was for a DC start relay to the control panel
A spare DC Motor
would cost about $400
Personally, I think DC motors will become more popular for high output RO systems as Green DC generation and battery storage
solutions continue to improve.