Great, thanks, BMatthews.

Low wing loadings means that we have plenty of area and that our wing needs creating less disturbance to the air in order to sustain the weight of the plane and any G forces associated to maneuvers.
Less disturbance means either less velocity through the air or less AOA or both, which directly relates to less drag (every type of drag).

That also means that any force coming from the air (gusts and thermals) has more influence on the airplane with low wing loadings, due to bigger aerodynamic areas and less inertia (high area to weight ratio).
That is a bad thing in the case of gusts for sport models and a good thing in the case of thermals for sailplanes.

http://www.youtube.com/watch?v=aVdoF4VbCFQ