But the rush ..I just flew low over a lake again this afternoon--no issues. I don't believe the optical sensor is used for height control anyway--more for position hold, like what an optical mouse uses. In any case, I've noticed that ultrasound seems to give a pretty accurate height reading off the water. Yeah, it's still a little nerve-wracking flying 50mph (from a 15mph tail wind) 5 feet off the water, as if something does go wrong, you'll have no time to react.
I like to fly over water as well but was scared vow would get screwed up from optical sensors reflecting off water. I'm thinking it's better to be safe than sorry by turning it off but haven't gotten a chance. I would like to hear from people leaving it on if they've seen any odd behavior with it close over the water?