One of my co-workers just got a $900 one (I don’t recall what brand) for his yard here in MI. he said its nice but it only does a random pattern every time it leaves its docking station which can leave areas uncut. it also has a setting that follows the outer perimeter* that makes sure at least that gets cut.
*The perimeter is set by a wire that has been buried and is hooked up to the docking station
But that defeats the purpose of a robotic mower, because the helicopter would need a pilot. Attach a cordless string trimmer (or 2 or 3+) to a Roomba, set it in the yard, and press “Clean”. The Roomba will even pick up the clippings!