The positives of inflatables you outlined are good but that type of craft have negatives as well. Anyone contemplating using one in a shtf situation should bear in mind the limitations as well.
First they are inflated craft, so they deflate as well. Usually when you don’t want it to happen. Being in a soft inflatable is comparable to pushing a rope. If the motor can’t be used for mechanical propulsion they must be rowed or paddled. Inflatable boats are normally flat bottomed and short making them very difficult to stay on course. Even a 100 or 200 yard passage is pain in the ass because they spin like a paper plate.
This is my opinion about engine noise. On the water you can hear a mouse fart. Except for open ocean along the coast, most bodies of water don’t have surf noise. The small waves on inland bays, the great lakes, rivers and lakes don’t amount to much. I lived on the Chesapeake Bay where it was 8 miles wide. At night boat motor noise could be heard for miles and miles. I always knew a boat was moving long before I could see it. Any noise that is mechanical and unnatural will attract attention.