I'm a C5 incomplete, T7 spinal cord injury person and today I was practicing going up and down curbs with my therapists when it all went wrong and I fell out of my chair. My SmartDrive MX2 stayed connected to the chair and because the connection to the chair rotates, it moves freely, allowing me to crash.
The weight of the smartdrive (12 pounds) is also probably why it was harder for me to get up the curb.