I am trying to buy two Starling 2 MAX drones for 5/4G research. They told me that they are having trouble with the GPS system on board. How inaccurate is the GPS? Also, what type of GPS issues are these? Can we add a 3rd party GPS module to this in the meantime? If we got these starlings would we be able to fix it after we procure it if you guys find a fix?