I can just see you now loading up a plane with your photo equipment/tent/junk for a weekend away and working out the balance sheet in Newtons.
Except for, he would not call it a "weight and balance" sheet, but a "mass and moment" sheet. And of course it would be corrected for the different gravitational "constants" across the globe.
Mind you, he'd never get there, because ATC will not allow his transit with a speed of 30 m/s and an altitude of 10.000 meters. And if he specifies a certain amount of dm3 with which to refuel his plane, he'd get very blank stares indeed from the refuellers.