The reality of helicopter flying is that most missions are local, VFR, and low altitude leading many pilots to shortcut through the pre-flight planning stage. Unlike most fixed wing flights, helicopters pilots rarely do a proper weight and balance unless they work for an operation that requires it, but does the weight and balance really matter?
The short answer is: Yes! Helicopter performance is affected by aircraft gross weight as well as the location of that weight. The center of gravity should be placed so that the aircraft fuselage could remain horizontal without any pilot inputs (think of it like two people of exact weight on a see-saw) except to correct for wind. If the center of gravity is to far forward, the nose will pitch down requiring back cyclic pressure to keep the aircraft level. Likewise, if the weigh is to far aft, forward pressure will be required. If the weight exceeds certain limits, the cyclic may not be able to compensate rendering the helicopter uncontrollable.
Pilots would be wise to remember that as the aircraft runs, and fuel is used, the center of gravity will shift. This is why you should always do a proper weight and balance before the flight to insure safe handling throughout.