I never found the braking distance to be a problem. To brake you basically just sit down and it kicks the motor into reverse. Because it uses the motor to rebalance the other way its much faster than if it were something like a disc brake.

I briefly owned one of these. Mine topped out at 32 kph (20 mph) but most models went faster.

IMO the biggest risk is if you accelerate too hard the engine cuts out even if you’re st high speed. And of course you’re leaning forward when it happens because that’s how you accelerate.