I take off on pavement, fly over grass, and land on pavement. Apparently, taking off or landing on grass puts a lot of stress on the tail drive gear and it can fail, causing your tail rotor to stop during flight. It's happened to me a couple of times. It's far preferable to crash on the grass though because if you hit pavement with carbon blades, there's a good chance they will get torn up. I've crashed on grass and the blades survived, despite having broken the blade grips.