Brad,
Head tracking is nice to have, but unless you plan to have someone else fly the quadcopter while you wear the goggles it's almost useless.
It is very difficult to fly a quadcopter or any rotor aircraft while using head tracking. Think of it this way. You want to fly forward, the quadcopter tilts forward and starts to move, naturally you tilt your head up in order to see the horizon straight ahead. Now, how do you know how much the quad is tilted forward? You have lost your visual reference of the horizon as related to the quad. Your head is compensating for any extra tilt the quad my have. This allows the quad to get into unusual attitudes very easily.
The same is true for flying FPV with the camera on a gimbal. The camera is always perfectly level, you have no idea what angle the quadcopter is flying.
One way around this, at least to use when flying using head tracking, is an on screen display with artificial horizon. This would give you back the visual reference you need to keep the quad level.
That being said I have head tracking on my drone airplane. This is different since the airplane is moving forward at all times, also the head tracking servos work using pitch and yaw. In order to turn an airplane you roll it. This gives you a good horizon view while turning no matter how you tilt your head. I also can see the nose of the plane and have a black line down the middle as an additional reference.
So lets summarize. Solo flight while wearing goggles and using head tracking on a rotor aircraft. Not impossible, but not a good idea.
FYI: Here is a nice side by side comparison of all the Fat Shark goggles.
http://www.fatshark.com/App_Theme/de...Comparison.png
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I'm not sure if you noticed or not, but the video transmitter that comes with the set you linked to only puts out 250mw. That isn't very much. My video transmitter is 600mw. 600mw seems to be the standard that everyone is using today.
Chris