I've had my Mavic for a couple weeks now and I'm a bit disappointed. It is a great quad and its super easy to fly, but the main reason I purchased it was for use with mountain biking and its following capability.
Mavic has two follow modes: active track and follow me.
Active track works ok if you have no obstructions, shadows, descending elevations and you present a strong contrast with your surroundings. But this is not really practical for mountain biking. Problems:
1. Active track can be done in wifi mode, but only in a follow orientation. It doesn't do profile or other following modes. Wifi mode is really the only way to do active track as carrying the transmitter with the phone attached while riding is not practical.
2. When riding a mountain bike, you frequently turn. This presents differing profiles to the Mavic. Mavic frequently gets confused and looses you.
3. Mavic does not adjust altitude to match your elevation when you go downhill. So, the further you go downhill, the farther away you get from Mavic and the smaller you appear. The smaller you appear, the more likely Mavic will loose track of you.
4. Mavic doesn't track you very well when you make quick movements or drastic direction changes.
5. One of the coolest features of Mavic is terrain follow... but it does NOT work in conjunction with active track. WTF?
Bottom line is, active track is marginally reliable at best. Once it looses track, it is a PITA to stop the bike, take manual control and reacquire.
Follow me mode only works with the transmitter connected to a phone or gps device. It's impractical to carry the transmitter and a phone together while riding. Also, follow me mode sucks because it doesn't keep you in frame. It will follow your gps location from your phone, but you may be completely out of frame while it does so.
Summary, if you are getting Mavic for its many other features, you'll find that it is a spectacular aircraft. However, if you are getting it for its following capability... not so much.
Recommendations to DJI:
1. Make terrain follow and active track work together.
2. Update Mavic's flight algorithms to keep the subject in frame during follow me mode.
3. Provide a separate "leash" transmitter that can be purchased that makes Mavic perform like other follow me drones.
4. Allow wifi active track to track profile mode
Love the drone... just not for the reasons I bought it.