This probably applies to all drones, but asking specifically about the Evo. The built in height limit is 400 feet if I recall correctly, but that is from take-off height. If you take off from a height of 2000 feet above sea level and fly it away from the takeoff point to an area where the ground is 1000 feet above sea level (these are all hypotheticals), I assume there is no issue descending to 1000 feet below your take off altitude. Is this correct? Also taking off from the same point referenced before and you are flying at -500 feet from take off altitude when RTH kicks in how does it behave? I ask because I could see the drone doing an auto RTH, going up 50 feet and promptly flying into a hill.