How do you deal with rolling shutter problem ? I do shoot according to 180 rule ( 1/50 sec @ 25 fps ), but still have problems when pooling out or pan... Premier has ' rolling shutter fix ', am not sure how much will that help... I've seen lot of footage that looks smooth, mine is sometimes quite choppy.

Could it be because I shoot in 2.7 k, heard that camera in fact works smoother when shooting in 1080...

It does not matter which resolution you work in, you will get rolling shutter effects. The answer is to work within the limitations of the sensor.  Specifically, avoid pans or rapid camera movements.

Hi Jack, please try to record when the drone is in hover status and see whether the camera works well. If yes, please refer Geebax's suggestion and practice more.

You could also shoot at 30 fps & 1/60th shutter which would help smooth things out a bit. And being fixed aperture you'll be using ND filters to set the exposure.