Hi David I currently have only one motor on my boat .The result being that I had to wait some 4 hours in blazing sun ,for a tow. CDI decided to stop working after 20 years. Lucky this happened on a fresh water lake.
Out at sea I have also prefer 2 x motors even with the higher running cost . Better than waiting for hours to get towed .
Love this quote of yours : " So ask me one engines or 2 and I will tell you about not needing to be towed twice." So true