Yamaha jetboat owner here, love mine. Cost of ownership is much lower than traditional drives. Salt water requires much more maintenance, esp ensuring boats/PWC sacrificial anode is kept good, salt water corrosion and rubber seals. Man I can't even tell you how not having to worry about, no hydraulics, no standard water pump, low draft. no prop to slice for foot on, great/safe for dogs.
Lastly, I honestly believe you should start with PWC's first, then build up to a boat.