It seems to me that a motherboard with a five year warranty shouldn't be too prone to overheating, but I agree that it's an expensive board.
The ASRock Extreme6 has better VRMs than the Extreme4; that's probably the one I'd choose.
It's because that thermal armor is designed to prevent heat. It actually traps it. And then to remedy the situation Asus included two cheap plastic 80mm fans that only circulate the hot air underneath.