That disclaimer is just so they don't get loads of people trying to return them after they blow them up trying to run electric bikes or skateboards. As long as you understand what you are doing its normally quite hard to break them.

The main thing is to not have your battery wires too long or the inductance of the wire causes a voltage spike which blows up the MOSFETs on the board. So long as you run them at least 2s below what they are rated for then you will *probably* be fine.

What are you using them to run? Weapon or drive? If you just mash the stick to full throttle instantly then it will pull a ridiculous amount of current which might cause it to explode too. So not good for a drive motor.