I have good omni antennas and a flight log to back it up. I will try to dig it up and post it here.
Edit:
Here is a screen capture of the logged flight. For this flight, the max distance was more like 260 meters (don't forget to calculate as sqrt(x^2+y^2+z^2)), but it also was never out of range, even with all the stunts I did that flight. It did have some dropped packets. At the end of the flight, you can see where I disconnected the flight battery; the RSSI went to -127 and RxGood went to 0 just before I stopped logging, yet it was better than that the whole flight. When the link is completely lost RSSI goes to -127 and RxGood goes to 0.
This is with vertically oriented linearly polarized omni antennas. I used a Nagoya 771 on the ground and a Nagoya 701 in the air (didn't even have ferrite beads). These are not ideal because they really need a ground plane / counterpoise. Simple dipoles like the stock OP antenna would be better than these.
Home was in the center of the runway, but the GCS/OpLink was off to the side of the runway. I was flying mainly up and down the runway and on the far side of the runway and the actual distances would be slightly farther than logged.
Screen cap shows x, y, z distances from Home, OpLink RSSI, OpLink RxGood (number of good packets in last 64 packets).
