Helicopters are affected by lateral imbalance more than airplanes. It a helicopter is loaded with heavy occupants and fuel on the same side, it could be out of balance enough to make it unsafe of fly. It is also possible that if external loads are carried in such A position to require large lateral displacement of the cyclic control to maintain level flight, the fore-and-aft cyclic control effectiveness will be limited.
Sweptwing airplanes are more critical due to fuel imbalance because as the fuel is used from the outboard tanks, the cg shifts forward, and as it is used from the inboard tanks, the cg shifts aft. For this reason, fuel-use scheduling in sweptwing airplanes operation is critical.