Just a couple days ago, I wanted to see how far away I could see the Mavic so I flew until I could no longer see it. At about 3000', I could no longer see anything. I kept my eyes on it the entire time. It was only a barely visible speck until I could no longer see it. Not sure exactly how high I had it, probably about 300' or so if I were to guess. It can be hard to find even at 200 feet sometimes if you take your eyes off it.
There are many, many cow fields around where I live and have filmed cows several times. They don't really seem to be bothered until you get within maybe 30 feet or so. They will look up at probably around 100 feet or so away, but then continue doing cow things, mainly eating lol. Would be a great tool for watching livestock.