I drove a Swedish boat that had an early Hundstatt , years ago.
Great at efficiency but it was a fish boat , converted to a yacht , so there was no gearshift.
Not usually a problem , but on starting , you had to remember YOU WERE IN GEAR!,
so if the boat needed a faster idle to warm up, you should have cranked to neutral thrust at that speed , before shutdown.
Plan on a tranny with neutral for our hi efficiency New build with CPP , if we can pull the construction costs off.