I've had bad luck with refurb mobos, but maybe I'm just unlucky. One caught fire, one just beeps at random intervals (and doesn't do anything else), and one seems warped (although it works fine...).
a motherboard would be the dead-last component that I would buy refurbished. When a motherboard is faulty, it usually has serious issues. It's usually not something they can just 'fix' by replacing a capacitor or two. The things usually go out in a dramatic blaze of glory.