The v1 would constantly nose dive on me when trying to fly up hills or doing 24mph+. Over time I realized that nosedives are usually the result of the over-exerting the engine to the point where it can no longer dedicate sufficient power to help you balance. You keep telling it to go faster so it goes faster and pushes back harder and eventually it cannot generate sufficient power to help you balance anymore. I wish they could program the board top out at a safe speed to prevent this but then again if I'm getting chased by a dog I want to be able to push the board faster and position myself against a possible nosedive. The is done by bending your knees more and shifting your front hip forward to keep the board accelerating while shifting your torso/head backwards to keep most of your body weight on your back leg. Keep your eyes on the road and shift to neutral 50/50 angle when going over significant bumps or lips.
I'm happy to report 0 high speed nosedives on the + and +XR. The power issues have been resolved and they push backer harder at higher speeds to prevent from mistakenly crossing the nosedive threshold. It should be noted that I only weigh 155lbs so heavier riders beware.