Do you actually ride one (I'm not being confrontational, I'm trying to understand if you're speaking from experience or also surmising)? I understand the principle of balancing a uni, but I also understand that when you land that hard, it may be difficult to keep the cycle under you. This is the same principle at work that makes it hard to keep your feet when you take a running leap off a drop. Sure, you can hit the ground with your legs braced forward to stick the landing, but often people will land too upright or even leaning a little forward, throwing them from their feet nad into a roll.

A high reverse torque clutch would maintain normal control except under extremely high reverse torque loads at which point it would act as a high-drag freewheel.