The Q500 flies well on the ST16, but the video screen has a lot of "artifacts" sparkling on it because of the difference in camera WIFI signal. Some are much better than others. If the CGo3 is on the latest firmware, it looks pretty decent. Older CGo3 firmware, not so good.
You might want to bind it and see how well you can see the screen before actually flying the drone.
The pictures and video recorded on the SD card are always normal, regardless of firmware version.