I'm a Phantom owner and I'm skeptical about those flying time numbers. I get 15-18 minutes on the drone by itself, but if you add the weight of the gimbal and camera (~0.5lb) the flight time goes down at least 4 mins, AND the gimbal needs power from the drone's battery too. I've heard the Phantom's flying time with the working gimbal is more like 6-8 mins. But if you know what kinda shot you want, that could be more than enough, just get lots of extra batteries (and those have dipped in price, you can grab one for $12).
I get muuuuuch more than 6-8 minutes with my phantom 2 and gimbal. I don't like to push it, so my longest flights are usually ~15 minutes, but I always have at least ~30% battery remaining. In addition to providing power to the gimbal, the phantom 2 is also giving some juice to the gopro, and to a fpv transmitter.
Do you own a Phantom or Phantom 2? The latter, which is referred to in the linked article, uses a much higher capacity LiPo battery (5,200mAh vs 2,200mAh) and consequently has double the flight time. However, you are correct in stating that adding a gimbal and camera will reduce flight time.
