Thanks for your thoughts. I would probably suggest that a ceramic lap is not just difficult, but close to impossible.
I personally like the batt for prepolish, but I would not like to deal with the ooops situation where a novice turns on the machine running the wrong way for the task at hand an brings down the stone with a bit too much enthusiasm.
From what I have read, the darkside does work well for many people when it comes to polish. I don’t happen to be one of them. But it may be the best bet for beginners. As you said, it is forgiving. Mistakes are unlikely to cause permanent damage to the lap as can be the case with other polishing laps. And the ability to switch from oxides to diamond and back is a plus for a situation where there may be more than one person sharing use of the faceting machine.