Note: Discussion of exceeding limits is made for education only, breaking the limits is illegal, unethical, and unwise
bvgs uses impeccable logic, and is quite correct:
The structurally the MGW is a fuzzy number, from a limits standpoint, because even a small 0.1 g bit of air turbulence gives you a 10% increase in all-up weight, if but for a few seconds. Clearly, the aircraft will not fall apart if you overload by a few percent. Similarly, the skids, engine mounts and other fixed bits of structure see loads on landing that are quite a bit higher due to the accelerations that they experience, so that a few percent is not a big factor. Nonetheless, each bit of increased loading due to overweight makes the structure experience a bit faster life degredation, so that the time limited components lose life faster, and will produce cracks earlier, perjaps within their safe life. For that reason, overload is a bad idea, but might look ok in the short term.
A worse situation is seen in the flight performance arena. Each pound of extra weight takes a great deal of performance off the table. Look to the hover charts and deduce the loss in hover IGE altitude for each 100 lbs of MGW, and realize that very quickly, a helicopter turns into a lead sled with even a few % overload. Hover altitude, tail rotor authority, climb rate and single engine performance all suffer rapidly with even modest increases in MGW above limits.