Will the Mavic Pro Overheat with the gimbal guard IN A FLIGHT??

No. It has a vent. They would not have made it clear and provided a protective rubber piece to keep it from getting scratched if it was not intended for that optional use. Plus I have seen official DJI videos where they are flying with it on.

If you mean gimbal COVER - no it will not overheat, dji says using it is optional and only has a negative effect on camera footage in certain conditions or when scratched.

if you mean the plastic protector that holds gimbal in place - then i think that could cause gimbal motor stress- it is a tiny motor and could overload and become defective or burn out.

Like Bekaru Tree replied, please confirm is it gimbal cover or gimbal lock, that is different. You can fly the drone will gimbal cover, but never fly the drone with the gimbal lock or the camera might get broken.

it should not overheat with the clear gimbal dome on it,  and no that small slit in the side isnt providing enough air to cool it if it was.   however i still wouldn't use it personally.. cooler the better, that being said maybe in the mist/rain, maybe in the snow... but probably not...

Hugh Jaynus Posted at 2017-8-24 06:09
No. It has a vent. They would not have made it clear and provided a protective rubber piece to keep it from getting scratched if it was not intended for that optional use. Plus I have seen official DJI videos where they are flying with it on.

OK BUT ,IS VENT BEHIND THE GIMBAL? WHEN I US GIMBAL COVER IN A FLIGHT IT BLOCKS THE VENT!!
IS IT SAFE FOR A DRONE?

DJI Thor Posted at 2017-8-24 22:10
Like Bekaru Tree replied, please confirm is it gimbal cover or gimbal lock, that is different. You can fly the drone will gimbal cover, but never fly the drone with the gimbal lock or the camera might get broken.

GIMBAL COVER

UMUT SEMERCI Posted at 2017-8-24 22:50
OK BUT ,IS VENT BEHIND THE GIMBAL? WHEN I US GIMBAL COVER IN A FLIGHT IT BLOCKS THE VENT!!
IS IT SAFE FOR A DRONE?

The gimbal cover might prevent the camera from wind to some extent. It is always users' preference to fly with the gimbal cover or not.

UMUT SEMERCI Posted at 2017-8-24 22:50
OK BUT ,IS VENT BEHIND THE GIMBAL? WHEN I US GIMBAL COVER IN A FLIGHT IT BLOCKS THE VENT!!
IS IT SAFE FOR A DRONE?

yes the vent is behind the gimbal
no - it does not block the vent
yes it is safe for a drone/mavic