Considering that most check-in agents would waive at least the first 10kg over the overweight limit, plus if you're travelling Business or First, they might even waive more! Butif you're also a Mrco Polo member, you'd get an additional 10kg, 15kg or 20kg for Silver, Gold and Diamond respectively.

Sometimes, it helps to just either pay the fare diff or maybe just upgrade to Business or First class using points (it seems the same requirements anyway), than to pay for excess baggage charges.