As others have pointed out, if you have a dinghy with an outboard you already have a justincase system- adding the complication of a motor mount to the transom of the big boat is an unnecessary complication.
Well, there is another way to look at this. I'm very aware of the limitations of an outboard regarding "hobby horsing" and the hassle of a stern outboard mount, but consider my situation.
I have a sweet, old Cal 30 that I'm hoping to take on a Great Loop trip next year. At present, I have a 10', air-floor dinghy with a 15 horse outboard. I've been debating about mounting a Garhauer mount on my stern to provide a secure storage point for the outboard when the dinghy is on deck. At about 75 pounds, I really feel the need to install one of these
to help manage the outboard and think that storing the outboard on a lift mount would allow possible emergency use as well.
While having no power from my A4 is an inconvenience at worst in many circumstances, having no power while spending two months and 1200 miles from Chicago to Mobile with the mast down is a bit more serious.
When you can't sail, you often depend a lot on your engine. If the engine won't run for some reason, using your dinghy powerplant seems like a very good idea in an emergency.
1965 Cal 30