Here in Brazil all Remotely Piloted Aircraft have to be registered at an government entity called ANAC and one of data needed from aircraft is the Maximum Take Off Weight (MTOW) (PMD - Peso Máximo de Decolagem in portuguese).... This is not the 740g weight of Mavic + battery....
This is the max payload the aircraft can handle and get a secure takeoff (acessories, adaptions, extensions etc etc..)
Why DJI omitt this info...
were can we get an secure data about this ?

"Why DJI omitt this info.."

I'm sure that DJI has tested MTOW during their development stage and I can think of 1,000 reasons why they wouldn't post it.

With a little effort, you could make that determination yourself.

Weight (Battery & Propellers Included)        
1.62 lbs (734 g) (exclude gimbal cover)
1.64 lbs (743 g) (include gimbal cover)
Thats the MTOW of the Mavic as lenses and the gimbal are not interchangeable and DJI do not support third party accessories used on it such as landing gear.

If you want a drone with a MTOW listed you need to look at the industrial grade drones that DJI offer such as the Matrice 200 series: -
Weight (TB50)        Approx. 3.80 kg
Weight (TB55)        Approx. 4.53 kg
Max Takeoff Weight        6.14KG

Giving that information would invite people to test it to the point of failure (and blame DJI).  Further, MTOW would depend on the altitude it was taking off from.  If it was given, I would assume it would be a sea-level number and you would have to calculate for anything above that.

AG0N-Gary Posted at 2018-1-18 11:33
Giving that information would invite people to test it to the point of failure (and blame DJI).  Further, MTOW would depend on the altitude it was taking off from.  If it was given, I would assume it would be a sea-level number and you would have to calculate for anything above that.

NOT giving this information will force people to test it.... and Yes, the values must be on sea level... but an aircraft that (at sea level) just can handle it´s own weight (and nothing more) will not fly or even take off in high altitude.  As comparisson an passenger car is not intended to transport cargo, but it have in his manual the max weight it support (which is the equivalent of MTOW for cars). So my impression is that DJI hide this info  not to "desencorage" people to "customize" (legaly or not) their equipments and blame DJI (the warranty terms are quite explicit on this) . But not revealing this data will permit that DJI make changes in parameters (all refered to the power capacity) and we can´t know about until comparrison. But if MTOW is showed any changes about it will be notice.  And that kind of reconfiguration of efficience parameters shoul easily be made by firmware update.

For what it's worth, I've seen a video of a Mavic being used to airlift another (crashed) Mavic out of tree branches. So Mavic can handle twice its own weight, plus the weight of the rope and a hook that was attached to it. Plus the resistance of the branches holding the downed Mavic.

Edit: here it is.


And here is a similar rescue of a Sparc by Mavic: