The only practical way to steer while moving astern is to steer with the engine. The ability to spin the engine around in its port to assist in steering is a great advantage over the inboard version of Ariels. None of the Alberg designed boats were designed to show finesse and grace while backing up. And while the Ariel - with her modified full keel - has a tighter turning radius than a battle ship while moving forward; in the close quarters of a marina, you may need to hasten her turns by twisting the engine. You want some resistance/friction to the engine's uncommanded turning in the port, but not so much friction that you can't turn the engine at all. When the eventuality arises that you need a really tight turn, it will be an emergency, and any delays may result in a collision.
Ariels have a great deal of yaw stability, i.e., resistance to turning. That is a wonderful feature in sharp ocean swells where they track like a train on rails, but not so good in a tight marina.
The biggest problem, at least with my Nissan Sailpro, is it's tilting while underway. The long shaft dragging in the water causes it to tilt way back, and to such an extent that the pull-to-start handle is buried out of reach, you can't shift into reverse gear from neutral, and the shaft angle contributes to shipping water into the boat. I found no way to correct this -- until I resorted to installing a piece of anchor chain across the shaft to prevent the behavior. Apparently Nissan thinks an engine that's marketed for use on sailboats still needs to tilt freely to prevent damage from a grounding -- as if it were installed on a dingie. The tilt "feature" is worthless on an Ariel, and I presume all other sailboats where the propeller isn't lower in the water than the boat's keel.
The only situation I can envision where the tilt feature would be helpful is when running over a crab pot line where it slips under the keel and then gets stuck on the forward surface of the engine shaft. And the engine still can't tilt back far enough to free the line. I have a knife on a pole ready for that situation. It's also good for fending off pirates ;-)