My first choice for mounting the Navio2 on a DJI F550 frame was on top, for ease of access, but I ended up putting it between the plates instead, because I thought it would be better protected there. I think this is turning out to be a bad idea for a few reasons.
Before I installed the Navio2, I was able to calibrate the compasses with no problem, but in the frame, compass calibration always gives unusable offsets.I see a lot of posts on compass offsets, so I am still investigating this.
Having seen raspicam related noise issues, I decided to pull the raspicam and test without it. 24 uncrews and screws later, the compass offset problem was unchanged, and now I cannot reattach the raspicam without taking all those screws out again.
Cannot see the LED clearly from all angles. Not a huge deal, but slightly annoying sometimes.